Major facelift for concrete muRascal

- All calls to muprim have been replaced by an explicit syntactic
construct.
- Several (mu)primitives can now be called as a function, e.g. size(lst)
- Improved println support: can now have variable number of arguments
and internal values (Coroutines, references, etc) are printed properly.
- Started with a top-level Compile API: compile, execute with various
keyword parameters to control debugging, printing, etc.
- Created a top-level set of examples that are organized as a test set:
the output of executing each compiled program is compared with the
output of an interpreted Rascal program.

muRascal is becoming a usable programming language!
Merge branch 'master' of https://github.com/cwi-swat/rascal.git

Conflicts:
	src/org/rascalmpl/library/experiments/Compiler/Rascal2muRascal/Examples/Example2.rsc