Added length heuristic to set matching

Now the last set variable is treated differently.
Speed-up is 5-10x compared to interpreter version.
Improved error message
Fixed error in set matching
Added two benchmarks
Added explicit types to avoid certain problems.
Fixed type error
Just one empty set now (thanks @davylandman)
Added Sudoku benchmark
Merge branch 'master' of https://github.com/cwi-swat/rascal.git
Added imports to make Sudoku benckmark compile; still does not compile
yet.
Implemented subscript on rel and lrel
Added support for anonymous indices in rel/lrel subscripts
Fixes #378.
Merge branch 'master' of https://github.com/cwi-swat/rascal.git
Possible fix to the issue #379.
Solved primtive generation for parameterized types.
Merge branch 'master' of https://github.com/cwi-swat/rascal.git
Another fix in importing rvm programs.
Fix to the CALLJAVA implementation: in case of @reflect tag, account for
the extra IEvaluatorContext parameter.
Progress with the Sudoku benchmark.