Mgvalleys: Remove riverbed sand placement from base terrain generation
Riverbed material placement moved to MapgenBasic::generateBiomes()
Document fields and add note that the biome API is still unstable
BiomeGen defines an interface that, given a set of BiomeParams, computes biomes
for a given area using the algorithm implemented by that specific BiomeGen.
This abstracts away the old system where each mapgen supplied the noises
required for biome generation.
NodeResolver name lists now belong to the NodeResolver object instead of
the associated NodeDefManager. In addition to minimizing unnecessary
abstraction and overhead, this move permits NodeResolvers to look up nodes
that they had previously set pending for resolution. So far, this
functionality has been used in the case of schematics for
serialization/deserialization.
- General code cleanup
- Unified object creation and loading
- Specifying objects in APIs is now orthogonal (i.e. anything can take an ID,
name string, or the raw table definition (and automatically registers if present
