Basic where clauses parsing.
Columns validation refactoring
Small Table refactoring
Added assert that columns are unique on table creation
Test: create table with duplicate columns
Test: insert with duplicate columns
Test: select all (currently does not work)
Added matcher sketch
Index matching sketch
Merge remote-tracking branch 'origin/where' into indexes

Conflicts:
	src/main/java/ru/spbau/mit/dbmsau/table/RecordSet.java
'select * from test where id = 3;' works