Contexts for If/Loops

[David Nolden]

Andreas:
Hmm that is currently not 100% supported by the du-chain, and real recursive 
searching would not be good performance-wise.

I've thought about this a bit, and I think the right solution would be a 
modification to the du-chain.

Specifically we should create a new mode of operation for DUContext, where the 
context is automatically imported into the parent-context.
Implementation-wise all this would mean is that the context should store its 
Declarations locally(needed for nice recompiling), but put them into the 
search-hashes starting at the own one, up to the first parent that is not in 
this mode.

That way the Declarations can be found on searches from within all contexts 
where it should be found, while still using the very efficient hash-search 
without any recursion.

greetings, David