Addition of large ejector control

An update of vacuum braking to correct some small errors identified, and addition of extra functionality, such as a working large ejector.

NOTE: This summary is insufficient for approval. Please provide a list of additional features and, if it wouldn't be obvious to a regular user, justification for their addition. Any bugs should be addressed through bug reports and associated fixed, not through blueprints.

NOTE2: The additional features were not listed here but have now been well received and tested in the forum (see "Read the full specification" below). CJakeman

Discussion: http://www.elvastower.com/forums/index.php?/topic/33205-vacuum-braking-update/