Do not use strings in VesselState gimbalExtDic

The dictionary now uses System.Type as identifiers.
Keys are PartModules types (ModuleGimbal), or object type for null
gimball.

Initialization is also moved into the static constructor as it is not
related to the object's instance.
Merge pull request #490 from ozraven/dev

Quick fix for handling engine parts with multiple gimbal modules.
Change how Velocity is calculated as mentioned in #478
Revert "Change how Velocity is calculated as mentioned in #478"

This reverts commit 1d5fb05db76a1c8e87c152b2e29c9504b8338277.
added a setting to limit window dragability to the titlebar, default off
changed the error playing a role whenever Force Roll in the ascent ap is using PYR or not because switching seemed often worse than sticking to either
shrunk the width of the SASS' surface input fields and also added the Heading Pitch Roll control also have +-0 and an additional one too, also made +/- do a change of 5 instead of 1 when the mod_key is held down when clicking
Fix landing site selection on other bodies than Kerbin
Merge branch 'dev' of https://github.com/MuMech/MechJeb2 into performance

Conflicts:
	MechJeb2/VesselState.cs
Do not throw exceptions in advanced transfer precondition check
Allow advanced transfer with no safe time margin
Fix the SpacePlaneAutoPilot to work on other bodies than Kerbin
0.90 changes
Merge branch 'dev' of https://github.com/MuMech/MechJeb2 into dev
FuelLines seem not to be used in editor anymore
Merge pull request #497 from xytovl/dev

Fix delta-v stats for 0.90
Redo the FuelLine fix with CModuleFuelLine.
Fix the NRE related to a not upgraded tracking station
Spelling error
Change how the lack of patched conics is detected
More change related to the patched conics lock
Update MechJebModuleAscentAutopilot.cs

The change I propose will help fix a long standing bug where a rocket would pitch up/down suddenly at the beginning of its coast to apoapsis phase. The cause of this is that the autopilot wants to change orientation to prograde. 

This action is seldom necessary and when performed at the beginning of coast, there is a high probability that the main engine will be firing/pulsing to maintain apoapsis. The end result can be an amount of momentum that no amount of reaction wheels or RCS will be able to counteract, ending in uncontrolled spinning.

The fix I propose here is to record its desiredVector as lastDesiredVector and then use that. (I chose AttitudeReference.INERTIAL because that was what was being used before but I'm not quite clear on usage here so maybe it needs .ORBIT? Or perhaps just not trying to change its current orientation at all would be better, but using lastDesiredVector seems to be working for me)