Added GCBench and the Richards benchmark from SOM++

Needed to adapt TaskState and TaskControlBlock to use accessors instead of direct field access for fields of the superclass. Not sure whether that is really intended, but most SOM parser seem to not like access to a superclass' fields.

Did not add #bitAnd: because #& already implements it.

Signed-off-by: Stefan Marr <git@stefan-marr.de>
Updated README to include build status of all implementations

Signed-off-by: Stefan Marr <git@stefan-marr.de>