Very slow progress with concrete matching.
Merge branch 'master' of https://github.com/cwi-swat/rascal.git
First concrete match with a variable just succeeded
Added get_children to MuPrimitive.
Added MATCH_APPL_IN_LIST, MATCH_VAR_IN_LIST for concrete matching
Implemented concrete lists (without separators)
Completed concrete matching
Merge branch 'master' of https://github.com/cwi-swat/rascal.git
Added handling of IndexOutOfBounds
Implemented rel/lrel subscript that is a set.
Fixed don't care (_) subscripts for rel/lrel
Updated test overview
Merge branch 'master' of https://github.com/cwi-swat/rascal.git
Prettyprint appl trees in string templates
Concrete lists are now also unparsed in string templates
Added ConcreteMatching example

Note: one failing example commented out.
First implementation of concrete terms.
Merge branch 'master' of https://github.com/cwi-swat/rascal.git