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
Close settings files and save them correctly
Ignore some mouse events sent from scrollbar to GUITable

Fixes #1567, #1806.
Add minetest.clear_registered_biomes() api
Schematics: Fix minetest.place_schematic() when defined by a Lua table
Mapgen V5: Fix use of uninitialized value in ctor
Fix regression (increase/decrease viewing range with +/- keys)
Restore finalColorBlend implementation in shaders.
Add space between client names in status text (client)

Before:
Server: version=0.4.10, uptime=190.5, max_lag=0.001, clients={user1,user2,user3,user4,user5,foobar,userplayedminetestthismorning}

After:
Server: version=0.4.10, uptime=190.5, max_lag=0.001, clients={user1, user2, user3, user4, user5, foobar, userplayedminetestthismorning}
Increase third person view distance

Signed-off-by: Craig Robbins <kde.psych@gmail.com>
Fix f6 debug/profiler display

After fonts were re-engineered the height of the f6 debug/profiler display would only display about 2-3 lines of text.
Make directional fog colors respect tonemap
Disable loading .mtl files. Theyre not used anyway.
Add flags and lacunarity as new noise parameters

Add 'absolute value' option to noise map functions
Extend persistence modulation to 3D noise
Extend 'eased' option to noise2d_perlin* functions
Some noise.cpp formatting fixups