Fixed failure to retrieve app icon for display

The get_faded_icon function now needs a second parameter indicating
the fading direction to properly deal with RTL languages. Add it so
the icon can be retrieved successfully.
Reference Issue #19
Merge pull request #22 from danielkza/fix-null-window

Avoid error-ing out when shell provides a valid focused app but no matching window
Merge pull request #20 from danielkza/fix-app-icon

Fixes failure to retrieve app icon for display #19
update to work with gs 3.10, lots of bugs corrected and code simplified
comments updated
Merge branch 'development'

Conflicts:
	extension.js
Enabling and disabling the extension now works as expected. Fixes issue #21.
fixed problem on enabling extension
minor bug fixes
minor code improvements
Fix missing _findTargetApp function (call the tracker directly instead)
Fix irregular whitespace
moved utility functions to their own script
Merge pull request #23 from danielkza/fix-findTargetApp

Fix missing _findTargetApp function (call the tracker directly instead) (fixes #21)
_findTargetApp() function added to StatusTitleBarButton when panel.AppMenuButton doesn't provide it (legacy support)
Merge remote-tracking branch 'upstream/master'

* upstream/master:
  _findTargetApp() function added to StatusTitleBarButton when panel.AppMenuButton doesn't provide it (legacy support)
  moved utility functions to their own script
  Fix irregular whitespace
  Fix missing _findTargetApp function (call the tracker directly instead)
  minor code improvements
  minor bug fixes
  fixed problem on enabling extension
  Enabling and disabling the extension now works as expected. Fixes issue #21.
  comments updated
  update to work with gs 3.10, lots of bugs corrected and code simplified
  Reference Issue #19
  Fixed failure to retrieve app icon for display