2.0.3.1

Thanks to github user @TuckMeIntoBread for this:
Fixes issue where staging fails to function correctly if a player deploys a vessel and exits the game before actually loading into that vessel

Overview
This pull request introduces improvements to the staging process for vessels deployed using KSTS. The primary adjustment is the invocation of StageManager.BeginFlight() when a KSTS-deployed vessel is loaded. While there are undoubtedly better methods to achieve this, the current solution works without requiring refactoring.

Known Issue
There is an outstanding issue where staging fails to function correctly if a player deploys a vessel and exits the game before actually loading into that vessel. When the game is relaunched and the vessel finally loaded, the staging is all on a single stage. I don't see a way around this without storing information about KSTS-deployed vessels in the save file or elsewhere on disk.