Define default options instead of checking if they exist
Move small zoom level threshold to a constructor option.
Reuglify
Merge branch 'add-zoom-option' of git://github.com/gmodev/google-maps-api-addons into gmodev-add-zoom-option

Conflicts:
	daynightoverlay/src/daynightoverlay.min.js
Merge branch 'gmodev-add-zoom-option'