shorten RATE message

not enough room to describe "fractions add up" -- maybe I can just fit
in the "remainder" to hint that it will be considered in future
upgrades?

vacuum_gambit.p8

@@ -761,15 +761,13 @@ between each
  shot when
   firing.
 
- fractions
- not shown,
-  but they
-  add up.
-
    is: ]]..tostr(c)..[[f
 minus: ]]..tostr(c-newc)..[[f
 ----------
-total: ]]..tostr(newc).."f",
+total: ]]..tostr(newc)..[[f
+
+remainder:
+  ]]..sub(tostr(newc-rawnewc),0,5),
   action=function()
    self.cooldown=newc>>16
    self.cd_remainder=newc-rawnewc