Move tools into a distinct folder.
Correct namespace (forgetting of use clauses)
Fix implode. (is_array() instead of is_string()).
Add condition support when _context->useModel is false
Correct break scope.
Fix unitialized var.
Use composer for dependency management.
Use PHPUnit. Add two tests.
Add tests.

Filter option can be an array of attributes.
Add Model::columns() method.
Model::delete() throws exception when $this is a "new" model.
Add __DIR__ in require statements
Model::toArray() converts DateTime to string.
Use __get() and __set()
Add Model::set(), alias of Model::modify()
Order By RAND() is possible.