1.4.0 - RC1

I've assembled the PRs tagged for 1.4.0 on my develop branch, and would like to merge them upstream. Change summary is as follows:

- Fix bug #63 (PR #64)
- Fix bug #41 (PR #60)
- Fix bug #65 (PR #66)
- Fix bug #69 (PR #72)
- Fix bug #42 (PR #62)
- Fix bug #36 (PR #57)
- Fix bug #18 and #19
- Correct deltaV & time calculation for NASA (ModuleEngineFX) engines (PR #74)
- Implement feature #77

If I've missed anything from this list that we said we would include, or if you have any other feedback, please let me know.

**EDIT** - This also disables the per-frame caching that I believe leads to the dreaded vessel duplication bug. This is only a partial application of madadam's original fix, but I found that this change was enough to prevent the map view glitching out, which I believe is the precursor to the main bug. See my comments at https://github.com/RemoteTechnologiesGroup/RemoteTech/issues/59 for further information.