hCenterWith: account for centered image width properly when computing additional right padding (see also #520)

Author: jtdaugherty

src/Brick/Widgets/Center.hs

@@ -60,7 +60,7 @@ hCenterWith mChar p =
            c <- getContext
            let rWidth = result^.imageL.to imageWidth
                rHeight = result^.imageL.to imageHeight
-               remainder = max 0 $ c^.availWidthL - (leftPaddingAmount * 2)
+               remainder = max 0 $ c^.availWidthL - (rWidth + (leftPaddingAmount * 2))
                leftPaddingAmount = max 0 $ (c^.availWidthL - rWidth) `div` 2
                rightPaddingAmount = max 0 $ leftPaddingAmount + remainder
                leftPadding = charFill (c^.attrL) ch leftPaddingAmount rHeight