integration of htm-subtree

[NiklasPhabian]

I merged pystare's master into htm-subtree-interface.

We should be able to build with the following recipe:

STARE_INSTALL_DIR=~/STARE_built_subtree/
export STARE_INCLUDE_DIR=${STARE_INSTALL_DIR}/include/STARE/
export STARE_lib_DIR=${STARE_INSTALL_DIR}/lib/

# STARE
cd
git clone git@github.com:SpatioTemporal/STARE.git
cd STARE
git checkout htm-subtree
mkdir build
cd build 
cmake -DCMAKE_INSTALL_PREFIX:PATH=$STARE_INSTALL_DIR -DSTARE_INSTALL_LIBDIR=lib -DBUILD_SHARED_LIBS=NO ../
make -j4
make install

# pystare
cd 
git clone git@github.com:SpatioTemporal/pystare.git
cd pystare
git checkout htm-subtree-interface
python3 -m venv ~/.virtualenvs/pystare_subtree
source ~/.virtualenvs/pystare_subtree/bin/activate
python3 setup.py build_ext --force
pip3 install -e . 

Where do we go from there? We need to do the following things.

1. the htm-subtree branch breaks some things in pystare. We need to fix those. A good way to start to find the broken things is by running the tests. I.e. run pytest from the pystare project root.
2. We need to illustrate the usage of the new functions in e.g. the notebook examples/joins.ipynb @TonHai1111 correct me if I am wrong. For now, the new functions are left_join(), inner_join(), and full_join.
3. We need to add tests in tests/.
4. We need to supplement the docstrings for our newly added functions in pystare/spatial.py

I created a draft PR here #74 any push to htm-subtree-interface branch will trigger the tests to be run.

I also created a Kanban to trace this project. https://github.com/SpatioTemporal/pystare/projects/4