Find a way to put instances into their own slice

[phischu]

We put every instance into its own slice. The problem is that the instance depends on both the class it is of and the type it is for. When compiling we would have to import the instance in either one so that it is propagated. But this leads to cyclic imports. Maybe instances really need their own very special treatment.

[phischu]

One idea is to add dependencies to all slices where a class or method is mentioned.

[phischu]

Ok, so if we do the above we again get giant ugly balls of code because instances use declarations and declarations if they mention methods depend on all instances.
Looks really bad, seems like we need to resolve type class instances.

[phischu]

We pair each instance either with the class or with the datatype if the class it builtin.

[phischu]

This probably would solve #72 #63 #48

[phischu]

Another approach is to use {-# SOURCE #-} imports to break the cycles.

[phischu]

Done with fb94f99 and a series of fixes after that.