Remove Screenwidth from default theme

Fix issue #288
Make defaultbutton and cancelbutton grey
White background instead of light grey
Fix a typo
Revert to original colours in CharView

The current theme has softer tones that are nicer to look at but too low
in contrast.
Removing hotkeys from tango resources file
Adding hotkeys back
Merge branch 'master' into themeworks

Conflicts:
	fontforgeexe/pixmaps/tango/resources
Merge pull request #1059 from fontforge/themeworks

Themeworks