Moved literal nodes to separate package and classes

Signed-off-by: Stefan Marr <git@stefan-marr.de>
Make the current instance of Universe accessible

WARNING: this is problematic when multiple instances of the Universe should be used, for instance for multiple independent interpreters on the same JVM.
Signed-off-by: Stefan Marr <git@stefan-marr.de>
Added folder with generated sources to ant file

Signed-off-by: Stefan Marr <git@stefan-marr.de>
Added Truffle-DSL jar to classpath

Signed-off-by: Stefan Marr <git@stefan-marr.de>
Added the first working type system.

For some reason, previous attempts always failed.

My current understanding is that we need the type system in order to map SOM types to Java natives, avoiding boxing. Especially to utilize the return-type specialization approach of Truffle.

Problematic is I think at the moment that the generated type system uses automatically generated asObject() and isObject() functions, and does override the once I provide.

In the literal nodes for Integer, String, and BigInteger, I needed to manually add an executeGeneric, which is more optimal than the generated one, but seems to point out problems with the overriding of asObject()/isObject().

[TODO-REPORT: investigate how the use of the type system works out eventually, report the problems with the overriding]

Signed-off-by: Stefan Marr <git@stefan-marr.de>
Make use of the new type system and introduce the new literal nodes that allow for return-type specialization.

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