Add contrib script for generating tcsh completion source

patchbomb: fix up confusion between strings and lists of strings.

bash_completion: try to use bash3 features if they're available This does NOT break completion for bash 2.05b (I haven't tested earlier versions)

bash_completion: small cleanup and bugfix _hg_count_non_option wasn't taking global options into account while counting non-option arguments. It also used only its first argument.

teach bash_completion about --cwd

bash_completion: better handling of aliases Instead of listing every alias in the big case..esac, use hg help to get the canonical name of the command.

bash_completion: update for new help output format

Add test-grep.out file for now.

Merge with TAH.

grep: extend functionality, add man page entry, add unit test. walkchangerevs now returns a two-tuple. Its behaviour is also extensively commented. The annotate command's getname function has been factored out to a new function, trimname, so it can be shared between annotate and grep. The behaviour of grep has been beefed up, so that it now performs a number of useful functions.