Pesto Junkie

Add:

• Add lovr.physics module (YES!)
• Add lovr.timer.getAverageDelta

Change:

• Change the window to no longer be resizable.
• Change the window to have an improved title.
• Improve error messages in several places.

Fix:

• Fix unintended interactions between window mirroring and shaders.
• Fix memory leak in require.
• Fix lack of clean up when using Mesh vertex maps.
• Fix occasional crash when transform stack overflows.
• Fix WebVR rendering bug when drawing controllers.