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
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
Simplify locating of boost-python for python 3

Use `${PYTHON_VERSION_MINOR}` to look for the correct boost-python version that corresponds to the specified python interpreter.
install the header file for the RDKit AvalonTools wrapper api
Merge pull request #363 from rvianello/install_avalontools_header

install the header file for the RDKit AvalonTools wrapper api
Merge pull request #354 from mcs07/boostpython

Improve locating of boost-python for Python 3
fix some minor inconsistencies in the naming of a few guc variables
add deprecations
Merge pull request #364 from rvianello/fix_guc_parameter_names

fix some minor inconsistencies in the naming of a few guc variables