Fix wrong pitch and bank value interpolation

Pitch and bank angle in CAircraftSituation are according to the
common aeronautical convention:
* Bank in degrees, positive = roll right
* Pitch in degrees, positive = pitch up

Microsoft Flight Simulator is using inverted angles, which was incorrectly
adjusted in the interpolator. This caused wrong values for X-Plane.
This angle correction is now moved into the MSFS specific plugins.
Additionally, so far the pitch and bank angles from own aircraft were
not yet corrected for MSFS. So we did send wrong values to the network.

refs #790

src/plugins/simulator/fs9/simulatorfs9.cpp

@@ -86,6 +86,9 @@ namespace BlackSimPlugin
             if (bank > 180.0)
                 bank -= 360;
 
+            // MSFS has inverted pitch and bank angles
+            pitch = -pitch;
+            bank = -bank;
             situation.setPitch(CAngle(pitch, CAngleUnit::deg()));
             situation.setBank(CAngle(bank, CAngleUnit::deg()));
             situation.setHeading(CHeading(pbhstrct.hdg / CFs9Sdk::headingMultiplier(), CHeading::Magnetic, CAngleUnit::deg()));