Distribute JimTcl using Docker

[mrv96]

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This PR aims to start (automatized) distribution of JimTcl through Docker.

I'm submitting a working Dockerfile, but probably this PR should be followed by Travis changes to build the Docker image and push it to the hub.

[msteveb]

This may be useful. Would be nice if we had a README that explains how to make use of this.

[mrv96]

I don't fully understand README necessity.

Docker's READMEs usually contain:

1. How to build the image
2. How to run the image

This is a very simple and standard Docker image. The commands that I used are:

docker build -t jimtcl . # build Docker image
docker run -it jimtcl # 100% equivalent to run `jimsh` in an interactive shell

These cover both point 1 and 2 and are trivial for whose know a little bit Docker.

Poit 1 could be a little bit improved explaining Dockerfile's ARGs, while point 2 could be a little bit improved with some examples. For instance:

• how to run if host's files are involved
• how to pass arguments to jimsh, even in non-interactive mode

However both examples solves quite standard Docker usage issues, which are already well covered by official docker run docs.

[msteveb]

Perhaps what I'm getting at it is how is it useful? Is there some use case of jimsh in a docker image that is interesting? (as it is primarily designed to be an embedded language where it is linked into some larger application).

[mrv96]

Personally I use JimTcl inside OpenOCD, but scripts development is easier without involving it. Developing inside a running JimTcl Docker container is the solution I adopted to exclude OpenOCD from the equation.