Improvements to the create and help commands

- `help` now lists all commands again (forgot `watch` und `unwatch` in last
commit)
- `help` (command) now works with the alternative shortcuts of the
commands
- `help` (command) now explains the different brackets
- `help` (command) now includes the shortcut of a command
- `create` now supports the creation of `FlxObject`s which require parameters
for their constructor