Mod profiling support

Config settings:
profiling = true/false (gather statistics)
detailed_profiling = true/false (break mod times to callbacks)

Chat commands:
save_mod_profile saves current statistics in debug.txt and shows on console (on default loglevel)
Fix caption of config mods button (simple menu)
Don't call a player event without having player to do a event for
Pass light sources in blue channel of vertex color instead of decoded light for all special drawtypes.
Plus some style fixes and optimizations.
Remove buildable_to nodes without dropping item when replaced by a falling node