I'm sick of all those #ifdefs in settings.c, and in any case plink

and pterm need at least one default setting to be _different_ (pterm
needs the default term type to be `xterm', while plink needs it to
be taken from $TERM). So here's a completely new alternative
mechanism for platform- and app-specific default settings. Ben will
probably want to check the integrity of the Mac port, since I've
fiddled with it without testing that it still compiles.

[originally from svn r2513]

unix/pterm.c

@@ -83,6 +83,23 @@ char *x_get_default(char *key)
     return XGetDefault(GDK_DISPLAY(), app_name, key);
 }
 
+/*
+ * Default settings that are specific to pterm.
+ */
+char *platform_default_s(char *name)
+{
+    if (!strcmp(name, "Font"))
+	return "fixed";	       /* COE_NORMAL works badly in an xterm */
+    return NULL;
+}
+
+int platform_default_i(char *name, int def)
+{
+    if (!strcmp(name, "CloseOnExit"))
+	return COE_ALWAYS;	       /* COE_NORMAL works badly in an xterm */
+    return def;
+}
+
 void ldisc_update(void *frontend, int echo, int edit)
 {
     /*