introduce is and equal methods. make equal as the main method.
limit and offset values also need to be prepared.
renamed the beginning and end of where as filter and end.
renamed 'Block' as 'Bracket' since they are inside round bracket (parenthesis that is).
updated README.md with new filter and bracket method names.
update README and make sure example works.
add more description text, fixed bad code, etc.
add $column in delete method.
add missing methods in SqlInterface that are present in Sql.
add save method in Query class.