Implement Matches and DoesNotMatch
Implement & improve some visitors

Implement:
* visit_Arel_Nodes_GreaterThanOrEqual
* visit_Arel_Nodes_GreaterThan
* visit_Arel_Nodes_LessThanOrEqual
* visit_Arel_Nodes_LessThan
* visit_Arel_Nodes_Or

Improve:
* visit_Arel_Nodes_Grouping