### TODO
- support for distinct
- command line interface
- better table print
- support for order by, offset, limit (allow column name in order by, validate)
- add count min and max functions, eg aggregate functions
- support for uniqueue indexes
- support for btree indexes
- support for parenthesis
- functions rtrim, ltrim, rpad, lpad
- support for *
- add pipe | token
- maybe to create iterator on table
- add exceptions and rename it to UsqlException
- class members should have prefix m_
- add const wherever should be