Release automation (for the most part)

[fluffynuts]

The RELEASING.md document attempts to layout each and every step, in order, that is required to get log4net updates to the users.

There are a lot of steps, but we can break the process up into a few sections where some could be automated:

1. update the documentation with any new information - could be partially automated: if nothing else, the new site for the new version should be created from the old one, leaving the only duty to update with changes. More often than not, the API doesn't change, so this would be automated for all intents and purposes, but obviously we might want to stop here to make modifications
2. new npm script: npm run prepare-release -> would do steps 2-12 of the linked RELEASING.md document
3. raise a vote on the logging mailing list - perhaps this could be "semi-automated" by generating an email from a template and invoking the system email handler, but this might not be worth it. At any rate, the voting process cannot be automated, so we'd have to stop here anyway
4. new npm script: npm run publish-release -> would do steps 16-19, once the vote has passed

build logic can be written in typescript or javascript, by adding gulp-style tasks in files under local-tasks (see existing tasks under that folder; tasks are run by zarro and I'm always happy to assist with this. To see a new shell task, run npm run zarro -- -- --create-task (the two --'s are required to get past npm's argument handlers and pass on to zarro)