Make QueryContext partially go through kernel API

o Make hasProperty use propertyKeyId
o Make removeProperty use propertyKeyId
o Make Cypher delete entity operations go through kernel
o Introduce TokenContext has a shared trait of {Plan,Query}Context
o Enhance TokenType and KeyToken to provide getId, getOptId, getOrCreateId functionality
o Make DeleteAction take a KeyToken argument
o Support for resolving property keys at plan build time
o Make expressions.Property use KeyToken property keys
o Make Cypher setProperty operation go through the kernel
o Replace prior LabelResolution
o Make CloseableIterator always return Maps and materialize Streams
o Make Cypher getProperty go through the kernel API
o Make dumpToString() reopen QueryContext as needed
o Rewrote MapPropertySetAction
Merge branch 'cykops' into 2.0-mandatory-tx
Documentation tests in Cypher