Added random tests for library functions for sets.
Added random tests for map library functions.
Extended Rascal expression syntax for list/string/node slicing
Added tests for slicing
- Extended list tests
- Added node and string tests
Implemented list/string/node slicing
Added new tuple case.
Merge branch 'list-slicing'

Conflicts:
	src/org/rascalmpl/interpreter/result/StringResult.java
	src/org/rascalmpl/library/lang/rascal/tests/Lists.rsc
	src/org/rascalmpl/values/LocalSharingValueFactory.java
Fixed a test
Added new test suite for expensive tests
Fixed generation of random node values

Also improved formatting of some messages.
Tests for node slicing now work with random test framework
Code clean up.
Added proper handling of type parameters to random test framework
Fixed test for maps
Regenerated AST classes using parser generator with adjusted ranges
Changed implementation of ranges in Results
Remaining regenerated AST classes
Fixed all uses of ranges in the library
Changed the default visibility of functions.
Addition to Cobra for dealing with type parameters.