Store escaped table name in SqlTable.
Add basic sql parser.

It can extract field expressions and aliases, from part and where part.
Refactored parser to a class.
Basic support for getting column types from sql.
Add from_sql constructor to SqlTable.
Allow column type hints when constructing SqlTable.
Parser test.
Fix a bug when parsing selects with only one column.
Refactor SqlParser.
Raise on unknown keywords.