Add Lua helper functions vector.apply(v) math.sign(x, tolerance)
Performance of main client loop up to 2x faster In places, up to 3 times faster

NOTE 1: This does not mean a 2x increase in framerate. Increase in fps may be up to 1-2fps
NOTE 2: This local 'caching' of settings is not optimal and an alternative solution will be worked on after 0.4.11 is released
Rewrite generate notification mechanism

Add support for notify-on-decoration
Clean up mapgen constructors
Clean up mapgen.cpp code style somewhat
Remove trailing whitespace from some files
Build for win32 & win64 on Travis too
Add workaround for failing clang build