Various changes related to keyword parameters
Further implications of keyword parameters for node.

The current (admittedly brittle but temporary) strategy is as follows:

- constructors always have as last argument a map with keyword
parameters
- nodes only have a map with keyword parameters as last argument when
keyword parmeters are present.

There are several new muPrimitives to decompose constructors and nodes:
- get_name_and_children_and_keyword_params_as_map
- get_children_and_keyword_params_as_values
Merge branch 'master' of https://github.com/cwi-swat/rascal.git