Removing all unsafe casts

- some of them are there to provide more definite type info
- and most of them to indicate the guarantee of a value being not null
There are removed because they should not be necessary, and will probably be removed from Graal entirely eventually

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

Conflicts:
	src/som/interpreter/nodes/ContextualNode.java
Remove caching from dispatch chains

This still keeps the chains, but they are always only the general case.

Signed-off-by: Stefan Marr <git@stefan-marr.de>
Fixing compilation of #dnu branch

Doesn't need to be optimized here, but should not hinder compilation.

Signed-off-by: Stefan Marr <git@stefan-marr.de>
Remove unnecessary dispatch chains to simplify further

Signed-off-by: Stefan Marr <git@stefan-marr.de>
Removed more of the unused dispatch chain infrastructure

Signed-off-by: Stefan Marr <git@stefan-marr.de>
Fix merge/rebase nonsense

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