Signed comparisons are now working (except for signed longs)

Fixed gen errors for bit &, | operators
Auto register collision detection was failing
Changed the default processor to a 16F877
Added regression test script "rt.sh" for regression testing a single file.

git-svn-id: https://sdcc.svn.sourceforge.net/svnroot/sdcc/trunk/sdcc@1428 4a8a32a2-be11-0410-ad9d-d568d2c75423