This greatly reduces the complexity of Settings code.
Additionally, several memory leaks were fixed.

Signed-off-by: Craig Robbins <kde.psych@gmail.com>

Leads to the following increases:
getSmoothLight() approx.     40% increase
getTileInfo() approx.        25% increase
MapBlockMesh::MapBlockMesh() 25-30%

Details:
- https://sourceforge.net/p/irrlicht/bugs/433/
- https://github.com/minetest/minetest/issues/1687#issuecomment-61368769
- https://forum.minetest.net/viewtopic.php?f=42&t=9190&start=125#p159364

In case when "settings.h" is included from "emerge.cpp" or
"environment.cpp", u64 type has "unsigned long" length because
previously <stdint> was included. When "settings.h" is included from
"settings.cpp", u64 has "unsigned long long" length because no <stdint>
was included previously. This leads to different signatures of "setU64" method
and linker cannot find appropriate symbol.

The best fix of this bug should be done in the Irrlicht, but as hotfix I
think this is OK and better than types changing.

Previously this bug didn't appear because there was no "settings.cpp" file and
implementation of all methods was done in the header file.

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

After fonts were re-engineered the height of the f6 debug/profiler display would only display about 2-3 lines of text.

Signed-off-by: Craig Robbins <kde.psych@gmail.com>

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}

Fixes #1567, #1806.

Add support for notify-on-decoration
Clean up mapgen constructors
Clean up mapgen.cpp code style somewhat
Remove trailing whitespace from some files

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

This is "Add name of node pointed at to debug #1677" by @rubenwardy updated to work with game.cpp after it was refactored.

Note: The unit test was technically incorrect for all platforms but passes due to implicit casting

Until a permanent fix can be developed

~3-4x faster

This indirectly optimises MapBlock:copyTo() which in turn improves performance of MeshMakeData::fill()

Right mouse button behaviour for craft/inventory If right mousebutton clicked once then don't drop single items into slots. If right mouse button has been clicked and held a second time, drop items as the mouse is moved. In the second case (automatically drop/place items as mouse is moved) only auto-drop into blank slots, or slots that contain the same item.

Signed-off-by: Craig Robbins <kde.psych@gmail.com>

 - Remove blank setting values when setting has a group
 - Pair setting values with groups in file when possible
 - Preserve user-set whitespace in setting objects
 - Delete setting value when setting NoiseParams group
 - Delete overwritten groups outside of lock

Add definable node_stone to biome API, mgv5, mgv7. Reduce and correct depth of mgv7 biomes. l_mapgen.cpp: add '#include mapgen_v5.h' because '#include mapgen_v7' is there. Improve underwater grass hack