Use character size scaling factors

The bounding boxes for characters can be scaled using "cwscale" and "chscale"
to scale the width and height respectively.

config.def.h

@@ -9,6 +9,10 @@ static char font[] = "Liberation Mono:pixelsize=12:antialias=false:autohint=fals
 static int borderpx = 2;
 static char shell[] = "/bin/sh";
 
+/* Kerning / character bounding-box mutlipliers */
+float cwscale = 1.0;
+float chscale = 1.0;
+
 /*
  * word delimiter string
  *