Expression evaluation
Join implementation.
Basic simple select implementation [untested]
Working simple select implementation.

A set of changes containing fixes in select code and DataShard.
SQL queries tester
Removed old jsqlparser usage example.
Merge branch 'basicSelect' into shard-prototype

Conflicts:
	src/main/java/pw/edu/elka/rso/storage/QueryResult.java
	src/main/java/pw/edu/elka/rso/storage/SqlDescription.java