Bug 435384 - Add support for 'transparent' colors
- Added SWT.COLOR_TRANSPARENT to get pre-defied transparent color.
- Refactored Windows color class
- Fixed Color JUnits

Change-Id: I3fcd2e82adfc20ef3a09fae0b11bc33da2e53be3
Signed-off-by: Niraj Modi <niraj.modi@in.ibm.com>