surface: Added Entity list overlay icon for F15.
surface: Made F15's gun bullet speed configurable from script.
surface: Made F15's shoot cooldown time configurable from script.
surface: Deleted apparently unused macros, because they're evil.

Also deleted apparently unused functions and constants.  We may revisit
when we revive some features, but they're way too old to translate
directly to C++.
Added ModelEntity class hierarchy between Entity and Autonomous.

We wanted to share codes for surface Entities which have Model and
rigid bodies for dynamics simulation, but not actually Autonomous
in space.  So we decided to insert the new class in the middle of
inheritance hierarchy.
Added drawCockpit() virtual method to Entity.

Also renamed wardraw_t to WarDraw, which have been using old naming
conventions.
Erased too old forward structure declarations and macro definitions.
Fixed ModelEntity.h and Autonomous.cpp fail to compile with Linux gcc.
Changed order of precedence for Player's camera mover cycle.

It now prefer cockpitview when the camera is chasing an Entity,
otherwise freelook.
surface: Added cockpit model to F15.
Added atmospheric pressure member function to WarField.

The default value is 0, which means in space.
surface: Added HUD display to F15's cockpit model.

Also added atmosphericPressure() definition to SurfaceWar.
It defaults to Earth's scale height at temperature of 270K.