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
Avoid error-ing out when shell provides a valid focused app but no window.
Fixes inconsistent indentation
Fix syntax error (missing closing bracket)
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
Merge branch 'development'

Conflicts:
	extension.js
Enabling and disabling the extension now works as expected. Fixes issue #21.