contrib/vim: add a syntax file for unified tests
This syntax file adds:
* Highlighting of comments, output, and commands (with sh highlighting
in commands).
* Folding for output and blocks of commands+output.
* Setting tab/indent settings to 2 spaces, because that's what's defined by the
unified test file format.
mq: removed -m from qpush help (Issue2401)
The -m option became deprecated in changeset
bcf90e712dc3,
but the option still appeared in the help line for the qpush
command