add tree functions for trimesh
vector/blas.h: Add comments and reformat
comment mpl assert for buffer
add beziers, svgs, utilities to core
exposed decimater types
Convert polygon code to nested arrays
Rename IdentityMap to arange to match numpy
geometry/traverse: Fix type of thickness for integer case
Rename NestedArray to Nested
geometry/traverse: Disambiguate traverse with single_ and double_ prefixes

Previously only the "tolerance" parameter disambiguated the singly and
doubly recursive overloads, which is dangerously confusing.  Now that
doubly recursive traverse is called double_traverse, the thickness
parameter is optional.
garbage collection with vertex id map, transform with matrix, from/to python for property handles
pull decimation modules into .h for external use
Fix reference counting order of operations for Ref assignment operator
add a get_prop helper fn
windows build