* Move function from closure to class method
* Bug has been fixed: Failed to execute 'inverse' on 'SVGMatrix': The matrix is not invertible
* Performance of frame changing has been increased due to UI containers had detached from DOM before their items were created
* Bug has been fixed: Defiant doesn't support dash (-) in xpath nodes (#53)
* Data validation on client and server (#51)
* Migration files have been added (#59)
* Big int migration file has been rewritten with Django syntax (#60)
* Some memory leaks have been fixed (#61)

- changed Content-type for save_job request to application/json, object…
- Adopted public PR - PASCAL VOC converter
- Added convert_to_mask.py script
- Fixed player continue plaing at the end of video, lock for editable object broke the client
- Same colors for shapes and menus, ability to change color for label or group
- Undo redo
- Added license header for all files
- Added .gitattributes file (critical for bash scripts)
- Fixed "Don't delete tasks if a user is deleted"
- More strict check for 'checkbox' and 'number' values
- Added convert_to_coco.py script
- Job statistic were extended. Blowradius was removed
- More strict labels verification
- Drag polygons by requirement, norm stroke opacity, easy box dragging
- Drawing with mouse outside the image area
- Fixed 7z support
- Boundig box size in drawer, switcheable grid
- Split tracks feature
- Fix flip parsing
- Update color set & color by label feature
- Add point for polygons feature
- Added context menu
- Polyshapes

Feature/pascal voc converter

unit testing, warns when using interpolation xml's or images with annotations different than bounding boxes

enable the import of picture with alpha channel

 - jpg doesnt support alpha channels
 - when importing pictures with alpha channel error shows up
 -- "Could not create the task. OSError: cannot write mode RGBA as JPEG"
 - fix error by converting "RGBA" to "RGB" before saving image

* Fixed 7z support. (#235)
* Added 'Development Environment' into CONTRIBUTING.md
* More strict verification for labels with attributes.
* More strict check for values of checkbox/number type of attributes.
* Added .vscode/launch.json

Changes:
- Fixed https://github.com/opencv/cvat/issues/14 (docker-compose down command as written in the readme does not remove volumes)
- Fixed https://github.com/opencv/cvat/issues/15 (All checkboxes in temporary attributes are checked when reopening job after saving the job)
- Fixed https://github.com/opencv/cvat/issues/18 (Extend contributing.md)
- Fixed https://github.com/opencv/cvat/issues/19 (Using the same attribute for label twice -> Stuck)

    * video from share hotfix & dump hotfix
    * Added contributors
    * Added screenshot, documentation, screencasts into README.md
    * Fixed GitHub documentation