Fix not adding the "include" directory to the spcomp search path.
Merge branch 'spcomp-include-path'
Merge pull request #113 from VoiDeD/spcomp-include-path

Fix not adding the "include" directory to the spcomp search path.
Copy callback lists before execution to allow hooklists to be mutated.
Sprinkle NULL entity checks around.
Merge branch 'sdkhooks-fix'