(buil, drnuke_const, opt_DRNUKE, show, show_nuke_build)

(show_nuke_capab, vers, xdvisible, build.t, Options.t):
Remove opt_DRNUKE and replace with the following check
drnuke_const > MIN_DRNUKE_CONST.
Set MIN_DRNUKE_CONST to 0.001 to prevent issues with tiny values.
Change the default drnuke_const to 0.0 because in the stock game
opt_DRNUKE was disabled.

include/nuke.h

@@ -35,6 +35,7 @@
 #define NUKE_H
 
 #define	N_MAXNUKE	20
+#define	MIN_DRNUKE_CONST	0.001
 
 struct nukstr {
     /* initial part must match struct genitem */