typo in documentation
add multi-component analog to component_for_entity

    also use a inline bit or in _build_bitmask, because hey is there any reason
    not to?
Merge pull request #1 from ponderstibbons/tivek_multiple_component_query

Add multi-component analog to component_for_entity
Merge pull request #2 from tivek/multiple_component_query

merge changes from the multiple_component_query branch: multi-component analog to component_for_entity query, tests and small fixes.