feature : add keyboard shortcuts : Events cleanup

+ Removed unused events
feature : add keyboard shortcuts : keycodes

+ moved keycode translation to KeycodeTranslator
+ made KeycodeTranslator more generic to handle 0-9 and a-z keys
+ small refactor in KeyboardEventService
feature : add keyboard shortcuts : initial impl

+ added shortcuts for all tools in ToolController
+ modified structure of tools in Controller to Array of descriptors to
allow to declare shortcuts directly when setting up the tool controller
fix : tool icon not selected when using shortcut
feature : add keyboard shortcuts : added help panel displayed on shift+?
feature : add keyboard shortcuts

+ cleanup of color management
+ colors are now stored in palette controller
+ drawing controller has a dependency on palette controller
+ UPDATE COLOR events have been removed (they were used only for
synchronizing palette and drawing controller)
Fix : add keyboard shortcuts : forgot misc keys
Fix : typo
feature : add keyboard shortcuts

+ decentralized shortcut declaration
+ each service/controller is now responsible for declaring its shorcuts
- documentation (cheatsheet) is still to be maintained manually
- init order matters (shortcutService has to be instanciated before
  everyone else) => should have a standalone KeyboardService singleton
  which is ready as soon as it is loaded
feature : add keyboard shortcuts

+ added shortcut to create new frames (n)
+ added shortcut to duplicate frame (shift+n)
Forgot to add duplicate frame shortcut to cheatsheet
Merge with master after PR zoom-level
Merge pull request #143 from juliandescottes/add-keyboard-shortcuts

Add keyboard shortcuts