Added elementTypeOf primitive.
Fixed tricky typing issue for multivars matching with a list[value]
Fixes #464: Addition inside a polymorphic function
Fixed error in MATCH_TYPED_ANONYMOUS_MULTIVAR_IN_SET
Fixed typing issue when matching multivars in set[value] similar to the
one for list[value]
 
See 8fc658a13ba458b71cebaafd4fc40337147f4704
Added tests related to  matching list[value] and set[value]
Updated test progress: we are at 96%

Note: these percentages are on the positive side since there are still
tests that have been commentented out (for various reasons).

We should add an Ignore attribute to tests to get a more precise count.
A grammar for unified diffs.
Added an @ignore attribute for compiled tests
Improvements related to @ignore
Updated test progress: at 98%

The probably final observation for this year: 98% of tests succeed now
(just 2% off the goal).

64 tests out of a total of the 2674 fail and a few dozen are commented
out for various reasons. So roughly still 100 failing tests to go.
Removed print statements
Another round of benchmarking

Performance is going down all the time. We are now at 10.7 x faster
compared to interpreted code. Mostly likely, recent necessary fixes to
the pattern matching code are the culprit this time.
Added MATCH_TYPED_VAR_IN_LIST and MATCH_TYPED_ANONYMOUS_VAR_IN_LIST
Removed some redundant type checks.
Optimized matching of multivars in lists
Profiling after list matching optimizations

We are now back at a factor 12.8x.
Merge branches 'master' and 'muAnd-muOr' of https://github.com/cwi-swat/rascal into muAnd-muOr