Add option to force software rendering instead of bombarding the user with fallback sessions (as on some cards, hardware rendering doesn't work)

git-svn-id: https://rebeccablackos.svn.sourceforge.net/svnroot/rebeccablackos@3085 56e3d1a8-0179-4092-b3e2-9fbbcda0c0a9
Add a boot option for passing wlmforceswrender
remove fallback sessions that are now achived by forcing the software render

git-svn-id: https://rebeccablackos.svn.sourceforge.net/svnroot/rebeccablackos@3086 56e3d1a8-0179-4092-b3e2-9fbbcda0c0a9
Document the strings passed to the kernel command line that the  WaylandLoginManager responds to

git-svn-id: https://rebeccablackos.svn.sourceforge.net/svnroot/rebeccablackos@3087 56e3d1a8-0179-4092-b3e2-9fbbcda0c0a9
Document the strings passed to the kernel command line that the  WaylandLoginManager responds to

git-svn-id: https://rebeccablackos.svn.sourceforge.net/svnroot/rebeccablackos@3088 56e3d1a8-0179-4092-b3e2-9fbbcda0c0a9