atom-based semantics

* from function based grammar to atom based grammar
* inference engine
* adapters for PostgreSQL, MySQL, Sqlite3, and SPARQL
* parse tree ordering heuristics
* David H.D. Warren's query optimization techniques
* Chat-80 demo
* Wikidata demo

0.2.0

v 0.2.0

0.1.0

Initial release with pipeline, parser and semantic composition