* mosquito-yasim.xml: make the inner wings symmetrical by using, for the right
wing, a positive length and a dihedral of 176 degrees (i.e. 180 - the dihedral
of the left wing). For flap and spoiler, use the invert attribute for the
control input.
Source: http://www.buckarooshangar.com/flightgear/yasimtut_surfaces.html
This moves the CoG from y=0.156 to y=0, i.e. centered, and makes the aircraft
level in straight-line flight; previously it would bank to the left by a few
degrees.
