Source SDK 2013 update 3

A very big update, may break the mod for a while.
Protobuf SH files included

Included the SH files for Protobuf
Added the feature-testing map test_ss_action

This map is only for feature-testing. It will be removed in the final
version of the game.
It's used to test the sonic screwdriver action mode.
Added the sonic screwdriver's action mode
Corrected indentation

Now the indentation is better.
Changed the .gitattributes and .gitignore

Now they recognize better Source Engine files and they ignore saves,
screenshots and other garbage created by the compiler.
Corrected and optimized the sonic screwdriver's action mode
Added the sonic screwdriver's lights mode
Added the sonic screwdriver's special mode
Registered the weeping angels' precache

Fixed the "Precache: too late" assert when spawning a weeping angel.
Added a new filter for the sonic screwdriver's modes