Implement components, entity, system
Cleanup entity.d
Unstable changes to entity.d
Fix array bounds errors
Fix entity manager clear
Add entity manager unittests
Add docs to gitignore
Add more unittests, fix accomodation code
Fix accomodate code, reduce wasted space
Move component state into manager, add range
Remove unnecessary Component class
Fix component mask range errors
Add opSlice
Add @safe, move ID out of Entity
Add entity filtering by component
Merge branch 'feature/entity-manager' into develop