Add footer

Options:
  --footer=STR             String to print as footer
  --footer-border[=STYLE]  Draw border around the footer section
                           [rounded|sharp|bold|block|thinblock|double|horizontal|vertical|
                            top|bottom|left|right|line|none] (default: line)
  --footer-label=LABEL     Label to print on the footer border
  --footer-label-pos=COL   Position of the footer label
                           [POSITIVE_INTEGER: columns from left|
                            NEGATIVE_INTEGER: columns from right][:bottom]
                           (default: 0 or center)

The default border type for footer is 'line', which draws a single
separator between the footer and the list. It changes its position
depending on `--layout`, so you don't have to manually switch between
'top' and 'bottom'

The 'line' style is now supported by other border types as well.
`--list-border` is the only exception.

src/util/util.go

@@ -97,24 +97,12 @@ func Min32(first int32, second int32) int32 {
 
 // Constrain32 limits the given 32-bit integer with the upper and lower bounds
 func Constrain32(val int32, min int32, max int32) int32 {
-	if val < min {
-		return min
-	}
-	if val > max {
-		return max
-	}
-	return val
+	return Max32(Min32(val, max), min)
 }
 
 // Constrain limits the given integer with the upper and lower bounds
 func Constrain(val int, min int, max int) int {
-	if val < min {
-		return min
-	}
-	if val > max {
-		return max
-	}
-	return val
+	return Max(Min(val, max), min)
 }
 
 func AsUint16(val int) uint16 {