Removing the BigInteger class at the language site

The main idea is to have only one unified class for integers at the language site. The VM takes care or representation etc.

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

Signed-off-by: Stefan Marr <git@stefan-marr.de>
Merge branch 'exp/remove-biginteger' of github.com:SOM-st/SOM
Remove all bit operations on Double (#& and #bitXor:) because they do not have any useful semantics.

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