gendoc: automatically create help for default extensions.
Adds a section in the hg.1 manpage and corresponding hg.1.html
file. Each extension is listed with its module docstring, followed by
the commands defined by that extendsion.
Creates help for extensions by extracting doc strings from the extension modules
and its commands.
Simple commands:
$ echo foo
foo
$ printf 'bar\nbaz\n' | cat
bar
baz
Multi-line command:
$ foo() {
> echo bar
> }
$ foo
bar
Regular expressions:
$ echo foobarbaz
foobar.* (re)
$ echo barbazquux
.*quux.* (re)
Globs:
$ printf '* \\foobarbaz {10}\n'
\* \\fo?bar* {10} (glob)
Literal match ending in " (re)":
$ echo 'foo (re)'
foo (re)
Exit code:
$ (exit 1)
[1]