Dave

Recognize standalone DMEs (type 13 in Robin's list).

Change from Dave Perry:

Allow YASim flight models to override the hard-coded fine and coarse

The "constrained" property for a mouse mode now actually constrains

Correct conditional so that FlightGear will compile without

Patch from Robert Swam to block enabling stencil at 16 bpp for glut

Reverted last changes, because they caused needle flips near 0.

Use angular momentum so that the compass can overshoot and oscillate