Docker local development setup (#210)

* Docker local development setup

* Add DEVELOPMENT.md  and update dev Dockerfile

* Delete setup.txt and fix DEVELOPMENT.md sequence

DEVELOPMENT.md

@@ -0,0 +1,37 @@
+# Development Guide
+
+## Docker local development setup
+
+You should have docker installed in your system, if not click [here](https://docs.docker.com/get-docker/).
+
+1. Go to diagrams root directory.
+
+2. Build the docker image.
+
+    ```shell
+    docker build --tag diagrams:1.0 -f ./docker/dev/Dockerfile .
+    ```
+
+3. Create the container, run in background and mount the project source code.
+
+    ```shell
+    docker run -d \
+    -it \
+    --name diagrams \
+    --mount type=bind,source="$(pwd)",target=/usr/src/diagrams \
+    diagrams:1.0
+    ```
+
+4. Run unit tests in the host using the container to confirm that it's working.
+
+    ```shell
+    docker exec diagrams python -m unittest tests/*.py -v
+    ```
+
+5. Run the bash script `autogen.sh` to test.
+
+    ```shell
+    docker exec diagrams ./autogen.sh
+    ```
+
+6. If the unit tests and the bash script `autogen.sh` is working correctly, then your system is now ready for development.

docker/dev/Dockerfile

@@ -0,0 +1,21 @@
+# use latest python alphine image.
+FROM python:rc-alpine3.12
+
+# install system dependencies.
+RUN apk update && apk add --no-cache \
+  gcc libc-dev g++ graphviz git bash go imagemagick inkscape
+
+# install go package.
+RUN go get github.com/mingrammer/round
+
+# add go bin to path.
+ENV PATH "$PATH:/root/go/bin"
+
+# project directory.
+WORKDIR /usr/src/diagrams
+
+# Copy the rest of your app's source code from your host to your image filesystem.
+COPY . .
+
+# install python requirements.
+RUN pip install black