Add brief description to most MSVTK classes.

Issue #43
Rename msvQTimePlayerWidget::onPlay() and onPlayReverse()

They are renamed into playForward() and playBackward() respectively.
Issue #43
Add brief description to CMake macros

Issue #43
Cleanup doxygen documentation generation

 * Use library version as a suffix for the html archive file name for
release versions.
 * Set msv as the prefix to ignore.
 * Reword short description
Closes #43
Merge branch '43-cleanup-documentation'

* 43-cleanup-documentation:
  Cleanup doxygen documentation generation
  Add brief description to CMake macros
  Rename msvQTimePlayerWidget::onPlay() and onPlayReverse()
  Add brief description to most MSVTK classes.