webcommands: define a dict of available commands

This will be used to hook web commands up to the help system. It also
makes web commands work similarly as CLI commands.

mercurial/hgweb/webcommands.py

@@ -20,6 +20,7 b' from mercurial.error import ParseError, '
 from mercurial import revset
 
 __all__ = []
+commands = {}
 
 class webcommand(object):
     """Decorator used to register a web command handler.
@@ -39,6 +40,7 b' class webcommand(object):'
 
     def __call__(self, func):
         __all__.append(self.name)
+        commands[self.name] = func
         return func
 
 @webcommand('log')