introduces docker deploy for running pysubyt command-line

initial stab at issue #25

Dockerfile

@@ -0,0 +1,11 @@
+FROM python:3.8-buster
+
+COPY ./ /pysubyt
+WORKDIR /pysubyt
+
+RUN python -m pip install --upgrade pip && \
+    pip install --no-cache-dir -r requirements.txt && \
+    python setup.py install
+
+ENTRYPOINT ["pysubyt"]
+

docker.md

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+TODO: describe how to use the docker thingy 
+
+
+build image
+
+```bash
+$ docker build . -t pysubyt
+```
+
+test if it runs
+```bash 
+$ docker run pysubyt --help
+```
+
+actually run pysubyt in the docker container accessing templates and input from the host
+
+```bash
+$ docker run \
+    -v $(realpath .)/tests/templates:/tpl \
+    -v $(realpath \.)/tests/in:/in  \
+    pysubyt -t /tpl -i /in/data.csv -n 01-basic.ttl
+```
+
+
+
+TODO consider a bash function dock-subyt() that takes arguments to execute pysubyt via docker
+- then provide that as a sh file that can be sourced
+- as well as have a ```make docker``` target to have image build + source that ```docker build -t pysubit && source pysubyt-docker-define.sh```
+
+
+dock-subyt 
+**  args to manipulate (all optional)
+   -t «path that should be made absolute and mapped to /tpl» 
+   -i «path that should be made absolute and mapped to /in»/inputname
+   -o «path that should be made absolute and mapped to /out»/outputname
+   -s KEY «path that should be made absolute and mapped to /set-${KEY}/inputname
+** args to pass through
+   -n «name to pass through»
+   -m «modifier to pass through»
+   -h
+
+