refactor and unify code

This fixes several bugs in both modules.

Utility/HumanNumber.hs

@@ -0,0 +1,21 @@
+{- numbers for humans
+ -
+ - Copyright 2012-2013 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Utility.HumanNumber where
+
+{- Displays a fractional value as a string with a limited number
+ - of decimal digits. -}
+showImprecise :: RealFrac a => Int -> a -> String
+showImprecise precision n
+	| precision == 0 || remainder == 0 = show (round n :: Integer)
+	| otherwise = show int ++ "." ++ striptrailing0s (pad0s $ show remainder)
+  where
+	int :: Integer
+	(int, frac) = properFraction n
+	remainder = round (frac * 10 ^ precision) :: Integer
+	pad0s s = (take (precision - length s) (repeat '0')) ++ s
+	striptrailing0s = reverse . dropWhile (== '0') . reverse