EMI: Implement head tracking.
EMI: Implement head limits.
EMI: Fixed Actor::getWorldPosition calculating the world transform incorrectly for attached actors.
EMI: Continuously update the look at vector when looking at an actor.
Merge pull request #947 from Akz-/emi-head-rebase2

EMI: Implement head tracking
GRIM: Set shadow userdata to nullptr when done with it.
GRIM: Implement a dim shader
GRIM: Implement GfxOpenGLS::dimRegion
Merge pull request #957 from klusark/dim

GRIM: Implement a dim shader
GRIM: Fix the dim shader compilation on android
ALL: ignore patch files in root directory of source
JANITORIAL: formatting headers
EMI: Fix trying to use the dim shader when it's not needed for EMI
EMI: Implement projected shadows.
EMI: Calculate actor bounding box correctly.

This is necessary for Actor::shouldDrawShadow to behave correctly, but
could also affect collision detection.
EMI: Enable shadow sprites.
EMI: Initialize the shadow color explicitly to black.
EMI: Add comment about what a previously saved value was.
GRIM/EMI: Make Light and SetShadow structs instead of classes.
GRIM/EMI: Use Doxygen style for the comments.