Enable splash screen with a tip of the day. Closes #259

Only one tip of the day right now.
Stub out remaining python API functions for D
Implement python saveNetwork (needs GUI listener though)
Update release notes.
Start centralizing test resource paths.
Add getOptionalInput() to Module
Merge branch 'master' into spire
You can now render 2 objects.

Spire supports any number of objects, but that will be unsupported until
we get dynamic ports.