Add checks for programs which are required for the test suite to run. All prerequisite programs are checked for existance, and if any are missing, a list of missing programs is printed, and the test suite is aborted. All programs currently used in the tests, except those in core-utils, are checked.

hgit -> hgk.py Move hgit to hgk.py - importing hgit as an extension created compiled hgitc, which was confusing - hgit existed to support hgk so it was slightly misnamed - removed executable bit as we no longer run it directly - add 'view' command so we can run hg view - change git-* commands to debug-* so hg help won't show them - chdir to repository root on view so hgk doesn't choke in subdirs

Add a favicon.ico, small version of the main HG image.