User-visible

User-visible

- knobs now continue to rotate when you hold down the mouse
- the middle mouse button makes knobs rotate much faster
- there are NAV1, NAV2, and ADF radios that can be tuned using the mouse
- there are standby frequencies for NAV1 and NAV2, and buttons to swap
- there is a crude, rather silly-looking DME, hard-wired to NAV1
- there is a crude, rather silly-looking autopilot that can lock
  the heading (to the bug on the gyro), can lock to NAV1, and can lock
  the current altitude
- the knobs for changing the radials on NAV1 and NAV2 look much better
  and are in the right place
- tuning into an ILS frequency doesn't change the displayed radial for
  NAV1

Code

- I've created a new module, sp_panel.[ch]xx, that constructs the
  default single-prop panel; this works entirely outside of FGPanel,
  so it is possible to construct similar modules for other sorts of
  panels; all code specific to the default panel has been removed from
  panel.cxx
- current_panel is now a pointer
- radiostack.[ch]xx keeps track both of the actual radial and of the
  selected radial (they will differ with ILS); the NAV gauges should
  not spin around automatically to show the actual radial (we need to
  do something similar with the autopilot)
- the panel is initialized fairly early
- make sure that standby frequencies also get initialized
- I've started combining and clipping small textures to save texture
  memory; there's a lot more to do, but at least I've made a start