tools, gendoc: Output small descr about module TOC.
stmhal: Add sys.platform string to PYBv1.0 (it's "pyboard").
doc: Document gc, sys, math, cmath.
doc: Fix up a few docs in sys module.
modsocket: .recv() returns bytes object.
py: binary.c: Properly implement alignment for native unpacked structs.
objstr: split(): check arg type consistency (str vs bytes).

Similar to other methods and following CPython3 strictness.
modzlibd: Decompress part of "zlib" module, based on miniz tinfl.c .
modzlib: Add tinfl.c from miniz SVN repo, r63.

The only change is line-ending convesion to LF.
tests: Add test for zlibd module.