Use Git version control on Launchpad

Why?
We would like to improve the experience of existing and new developers working on the source, and integrations with other systems such as bugs and blueprints, and the automated build system.

How?
To do this, we are going to migrate from the existing Subversion repository hosted by uktrainsim.com, to a new Git repository hosted by both launchpad.net and GitHub.

What?
The Subversion repository has a test Git conversion hosted at both of these locations:

- https://code.launchpad.net/or
- https://github.com/openrails/openrails

These repositories are identical; they have been created by taking the existing Subversion repository, converting it using the standard “git-svn” tool, applying an additional line-ending conversion, and creating the standard “Git flow” branches (develop, master, and release/* for each release). The line-ending conversion is because Git works better with Unix line endings in the repo, but the “git-svn” conversion process leaves our existing Subversion Windows line endings in place.

Discussion: http://www.elvastower.com/forums/index.php?/topic/27882-use-git-version-control-on-launchpad/
Poll 2016-05-21: http://www.elvastower.com/forums/index.php?/topic/28612-are-you-ready-to-use-git-source-control-for-open-rails/
Poll 2017-07-23: http://www.elvastower.com/forums/index.php?/topic/30584-are-you-ready-to-use-git-source-control-for-open-rails/
Roadmap: https://trello.com/c/ZtL6Dc5q/169-use-git-version-control-on-launchpad