Add maya style navigation scheme to 3d vieewport
Disable transform operation when navigation
Fix bug in 3d navigation scheme selection; Add modo navigation scheme
Keep selection from been cleared when navigating in 3d viewport

Conflicts:
	tools/editor/plugins/spatial_editor_plugin.cpp
Hold shift to speedup pan/zoom in maya navigation scheme
Merge pull request #237 from marynate/PR-maya-nav

Maya and modo style navigation