startmissiles(): 
Added 
	float vectx, vecty;
	vectx = (float)cos(vector[temp].theta) * vector[temp].r;
	vecty = (float)sin(vector[temp].theta) * vector[temp].r;
and figured the starting velocity based on these. (Prevent round-off errors on starting velocity.)

Added planet bitmaps, with a -p switch. The default is on; -p gives solid white planets.
(load bitmaps in initwindow(), check for switch in main(), give each planet a random surface in makeplanets(), use bitmap in drawplanet().)

Added window title.

Removed checking for StructureNotify events, and put GAME_EVENT_MASKS in pregame() instead of specific masks (initwindows(), xgrav.h)

Added
#define BUTWIDTH (69)
#define BUTHEIGHT (27)
#define BUTWIDEWIDTH (128)
and changed initwindows(), pregame(), game() to use them

Removed redundant 
    for (temp = 0; temp < numplayers; temp++) 
	drawship(playernum, temp);
from redrawm1().

Added a "zoom" button in initwindows(), and procedures redrawm1z(), drawshipz(), drawplanetz(). Everything fixed for zoom window to work.

Added 
#define COARSELIMIT (450.0)
#define SQUARECOARSELIMIT (202500.0)
and added code to calcgrav() to do coarse calculation when missile is beyond this limit

Changed *distance() functions to remove temporary variables

Generalized bitmap-loading code; the directories to load bitmaps from are now specified solely in Makefile