add downloads/ in Distribution / packaging

Add .gitignore rules for Symfony3

Symfony3 (and some versions of Symfony2) come with a new directory structure.
This updated version of Symfony.gitignore supports this new directory structure
as well as the old one.

The old Symfony.gitignore has been removed (a383e550) as Symfony 1 is no longer
supported.

Update Dart.gitignore

Add in rule for .buildlog

Added recommended gitignore rules from Craft

added: rules for ignoring precompiled headers for C/C++

Quoting from http://symfony.com/legacy

  The symfony 1.x branch of the framework started in 2005 and the latest stable
  version and long term support release is symfony 1.4. As of November 2012,
  symfony 1.x is not maintained anymore and you are encouraged to have a look
  at Symfony2 for any new projects.

Amends #1165

Add *.Rproj for RStudio users

RStudio - the only real R IDE, and an incredibly commonly used environment for R, particularly since it has git support - uses .Rproj files in projects, that follow the pattern projectname.Rproj. Adding *.Rproj to capture these and exclude them.

Add ebin, rel example, concrete dev mode, .rebar

add Windows shortcut files

Add ignores for bower-rails

New version of eledmac on CTAN adds new extension file

Ignore *.converted-to-* files in TeX

Fixed binary gettext files rule: .po -> .mo

ignoring new Magento 1.9 default theme

Create LyX.gitignore

Ignores *.lyx~ (crash recovery) and *.lyx# (timed autosave) files generated by LyX - the document processor.

Create Momentics.gitignore

Updated Zend Framework gitignore as per docs

Update Unity.gitignore

Remove trailing space

Updated link in Node.gitignore

Updated link for the dependency directory from [this](https://npmjs.org/doc/faq.html#Should-I-check-my-node_modules-folder-into-git) to [this](https://www.npmjs.org/doc/misc/npm-faq.html#should-i-check-my-node_modules-folder-into-git-).