Support for **kwargs in User Keywords

I created a Robot Framework branch which supports defining \**kwargs for User Keywords
(and also for Dynamic Test Libraries):

https://bitbucket.org/userzimmermann/robotframework/commits/branch/userkwargs

This RIDE branch adapts this support.
Currently it uses this syntax:

    ${arg} | @{varargs} | ${{kwargs}}

This creates a ${kwargs} Dictionary for the Keyword body.
The syntax can easily be changed in the robot code (see README).

I didn't touch the bundled robot. This isn't compatible anymore.