Color class now has alpha. New filesys method. Improved extras. Fix BCs.

- Added alpha component to Color class. Now primitives can draw with
some translucency.
- Added static methods to convert Colors from/to hex triplets and float
arguments.
- Fixed isFilenameDirectory/Archive() when passing a non-existant
filename (they now return false instead of throwing an exception).
- Added fgeal::setWorkingDirectory() function.
- Reworked Menu class color scheme to be more customizable. Also
improved behavior when drawing borders and when drawing entries that are
longer than the menu's width.
- Improvements to the Sprite class.
- Fixes to some eclipse build configurations. Also added some new.
- Some minor fixes.