Raise precedence of property lookup

Now higher than IN. Fixes #1295.
Allow both escaped ' and " chars in string literals

Regardless of the quote type used to represent the string literal. Fixes #1291.
Add error label for RelationshipDetail rule

Fixes #1297
Remove ExecutionEngine.execute(AbstractQuery, ...)
Remove ExecutionEngineHelper.parseAndExecute

(replaced with execute)
Split PlanDescription to have a minimal external interface
Add CypherCompiler interface

Moves parts of ExecutionEngine into versioned CypherCompiler
wrappers.
Error message grammar fix
Completely remove the label choice syntax from pattern docs.
Tagging for version 2.0.0-M06
Back to development version.
Merge pull request #1289 from cleishm/no_query_execution

Remove ExecutionEngine.execute(AbstractQuery, ...), split Plan Description and add CypherCompiler
Merge pull request #1293 from cleishm/string_quotes

Allow both escaped ' and " chars in string literals
Merge pull request #1296 from cleishm/property_precendence

Raise precedence of property lookup
Merge pull request #1300 from cleishm/error_labels

Add error label for RelationshipDetail rule
Added a functional test for label recovery.

The bug is already fixed in earlier commits, so this is just another test
for confidence and regression ensurance.