tried to move query execution over multiple contexts from query processor to the ContextIndex. Since the ContextIndex is still pure we should be able to parallelize here. Special functions like range or allDocuments are still todo
removed Fuzzy option from SearchOp enum, since we don't have such an operator within the StringMap
PrefixTreeIndex now uses correct mapping from SearchOp to StringMap
using strict StringMap now
cleanup
fixed fuzzy phrase search