Merge pull request #562 from taketwo/add-contributing-guide

Add a contributing guide

CONTRIBUTING.md

+# Contributing to PCL
+
+Please take a moment to review this document in order to make the contribution
+process easy and effective for everyone involved.
+
+Following these guidelines helps to communicate that you respect the time of
+the developers managing and developing this open source project. In return,
+they should reciprocate that respect in addressing your issue or assessing
+patches and features.
+
+
+## Using the issue tracker
+
+The [issue tracker](https://github.com/PointCloudLibrary/pcl/issues) is
+the preferred channel for [bug reports](#bugs) and
+[submitting pull requests](#pull-requests), but please respect the following
+restrictions:
+
+* Please **do not** use the issue tracker for personal support requests (use
+  [mailing list](http://www.pcl-users.org/)).
+
+* Please **do not** derail or troll issues. Keep the discussion on topic and
+  respect the opinions of others.
+
+
+<a name="bugs"></a>
+## Bug reports
+
+A bug is a _demonstrable problem_ that is caused by the code in the repository.
+Good bug reports are extremely helpful - thank you!
+
+Guidelines for bug reports:
+
+1. **Check if the issue has been reported** &mdash; use GitHub issue search and
+   mailing list archive search.
+
+2. **Check if the issue has been fixed** &mdash; try to reproduce it using the
+   latest `master` branch in the repository.
+
+3. **Isolate the problem** &mdash; ideally create a reduced test
+   case.
+
+A good bug report shouldn't leave others needing to chase you up for more
+information. Please try to be as detailed as possible in your report. What is
+your environment? What steps will reproduce the issue? What would you expect to
+be the outcome? All these details will help people to fix any potential bugs.
+
+Example:
+
+> Short and descriptive example bug report title
+>
+> A summary of the issue and the OS environment in which it occurs. If
+> suitable, include the steps required to reproduce the bug.
+>
+> 1. This is the first step
+> 2. This is the second step
+> 3. Further steps, etc.
+>
+> Any other information you want to share that is relevant to the issue being
+> reported. This might include the lines of code that you have identified as
+> causing the bug, and potential solutions (and your opinions on their
+> merits).
+
+
+<a name="pull-requests"></a>
+## Pull requests
+
+Good pull requests - patches, improvements, new features - are a fantastic
+help. They should remain focused in scope and avoid containing unrelated
+commits.
+
+**Please ask first** before embarking on any significant pull request (e.g.
+implementing features, refactoring code), otherwise you risk spending a lot of
+time working on something that the project's developers might not want to merge
+into the project. Please read the [tutorial on writing a new PCL class](http://pointclouds.org/documentation/tutorials/writing_new_classes.php#writing-new-classes) if you want to contribute a
+brand new feature.
+
+<a name="checklist"></a>
+### Checklist
+
+Please use the following checklist to make sure that your contribution is well
+prepared for merging into PCL:
+
+1. Source code adheres to the coding conventions described in [PCL Style Guide](http://pointclouds.org/documentation/advanced/pcl_style_guide.php).
+   But if you modify existing code, do not change/fix style in the lines that
+   are not related to your contribution.
+
+2. Commit history is tidy (no merge commits, commits are [squashed](http://davidwalsh.name/squash-commits-git)
+   into logical units).
+
+3. Each contributed file has a [license](http://pointclouds.org/documentation/tutorials/writing_new_classes.php#licenses) text on top.
+
+### Suggested process
+
+Adhering to this process is the best way to get your work included in the
+project:
+
+1. [Fork](http://help.github.com/fork-a-repo/) the project, clone your fork,
+   and configure the remotes:
+
+   ```bash
+   # Clone your fork of the repo into the current directory
+   git clone https://github.com/<your-username>/pcl.git
+   # Navigate to the newly cloned directory
+   cd pcl
+   # Assign the original repo to a remote called "upstream"
+   git remote add upstream https://github.com/PointCloudLibrary/pcl.git
+   ```
+
+2. If you cloned a while ago, get the latest changes from upstream:
+
+   ```bash
+   git checkout master
+   git pull upstream master
+   ```
+
+3. Create a new topic branch (off the main project development branch) to
+   contain your feature, change, or fix:
+
+   ```bash
+   git checkout -b <topic-branch-name>
+   ```
+
+4. Commit your changes in logical chunks. For any Git project, some good rules
+   for commit messages are
+
+   * the first line is commit summary, 50 characters or less,
+   * followed by an empty line
+   * followed by an explanation of the commit, wrapped to 72 characters.
+
+   See [a note about git commit messages](http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html)
+   for more.
+
+   The first line of a commit message becomes the **title** of a pull request on
+   GitHub, like the subject line of an email. Including the key info in the
+   first line will help us respond faster to your pull.
+
+   If your pull request has multiple commits which revise the same lines of
+   code, it is better to [squash](http://davidwalsh.name/squash-commits-git)
+   those commits together into one logical unit.
+
+   But you don't always have to squash -- it is fine for a pull request to
+   contain multiple commits when there is a logical reason for the separation.
+
+5. Locally merge (or rebase) the upstream development branch into your topic
+   branch:
+
+   ```bash
+   git pull [--rebase] upstream master
+   ```
+
+6. Push your topic branch up to your fork:
+
+   ```bash
+   git push origin <topic-branch-name>
+   ```
+
+7. [Open a Pull Request](https://help.github.com/articles/using-pull-requests/)
+    with a clear title and description.
+
+8. After your Pull Request is away, you might want to get yourself back onto
+   `master` and delete the topic branch:
+
+   ```bash
+   git checkout master
+   git branch -D <topic-branch-name>
+   ```
+
+**IMPORTANT**: By submitting a patch, you agree to allow the project owners to
+license your work under the the terms of the [BSD License](LICENSE.txt).