Add BiomeManager, OreManager, DecorationManager, and SchematicManager

Split up ModApiMapgen::l_register_decoration()
Define and make use of CONTAINS() and ARRLEN() macros

This also cleans up settings a bit

Remove flagmask field from set_mapgen_params table
Add small bits of needed documentation

MapgenParams is no longer a polymorphic class, eliminating the need for messy and bug-prone reallocations.
Separation between the common and mapgen-specific parameters is now strongly defined.
Mapgen parameters objects are now properly encapsulated within the proper subsystems.

the following:
1. String concatenation in guiMainMenu.cpp - it is required for all
individual strings to be of the same type <unicode/non-unicode>; adding
explicit L qualifier before the other strings.
2. Correcting type of BlockMakeData to struct in place of class forward
declarations. This information is used for name decoration by Visual
Studio, leading to linker errors in case of mismatches.
3. Windows headers define max as a macro somewhere, leading to a compile
time error in profiler.h; using () around function to prevent macro match
from occurring.