First try to integrate the binary instances for our existential types.
There are still some things to figure out - read more at #21
added typeable instances for specialized inverted index implementations
bugfix
bugfix
added testcase for Interpreter load/store operations
introduced a seperate datatype ContextType for contexttypes instead of using an enum.
We were able to define custom contexttypes with custom index implementations before, but it had some limitations.
Validation for example was tightly coupled with the CType and unable to change for different index or contexttype implementations.
It's likely that one, implementing it's own index, wants to implements it's own validation method as well.
That's an easy task now.
bugfix: forgot to reload schema after LoadIx Command
added testcase for binary instances of ContextType/ContextSchema
bugfix: load / store Commands exchanged
Cleanup
Merge branch 'existentialBinary'

Conflicts:
	searchengine/test/Analyzer.hs
	searchengine/test/Interpreter.hs
Cleanup and minor refactoring
Move Typeable and Fingerprint Binary instances into separate modules