Merge pull request #48 from piti118/master

update readme to inumpy
code cleanup and begin support for selection
clean up BetterChain.h
initial tests of selection
shrink array if selection was applied
test of selection with chain of two files
put test ROOT files in root_numpy/tests/data and scripts in root_numpy/tests/scripts
activate branches used by the selection formulae
original branch status is preserved
set default arg values (for selection=None) at the python level in root_numpy.py
better exception if requested branch does not exist
make test data generation scripts a compiled executable
add support for vector<bool>
declare type in Cython and add html output to .gitignore
suggest list_branches to see available branches
selection with TMath
use NumPy-style docs and PEP8
minor edits
NumPy doc style
include numpydoc sphinx extension