Fixes #351
add mol_numheterocycles() to cartridge;
part of #351
Update python implementation of atom pairs to reflect #334. This code probably should be deprecated at some point
release note update
Fixes #352
update release notes
Improve locating of boost-python for Python 3

The name of the boost-python library can vary depending on how it is installed. For example, Homebrew on OS X installs boost-python as  `libboost_python` for python 2 and `libboost_python3` for python 3. I believe Ubuntu installs separate `libboost_python-py27`, `libboost_python-py33`, `libboost_python-py34`, etc.

This commit improves the way RDKit searches for boost-python when installing for Python 3 by using a list of commonly used install names: "python-py34", "python-py33", "python-py32", "python-py31", "python3" are tried in turn, before falling back to the previous behaviour of just using `libboost_python`. A command line option `RDK_BOOST_PYTHON3_NAME` is also added to provide a way to specify a custom boost-python library name.
add Chem.Draw.MolToQPixmap
Fixes #357
tell the InChI code not to generate aux info when it is definitely not being used
add Darmstadtium isotope support in honor of the UGM
add multiconf pdb writer (as multiple models)
fix ENDMDL
support multiconf PDB read
allow transfer to pymol via PDB to be forced
merge
Fixes #360
Merge pull request #355 from mojaie/qtcanvas

add Chem.Draw.MolToQPixmap
update a couple docstrings
update release notes