Added clearance to the programming jig

It was too tight for MacroFab's routing tolerances before, so some
boards didn't fit well.  Now they all fit just fine, making me a happy
camper.

programming-jig.scad

  * 3D-printed part of a PD Buddy programming jig
  */
 module programming_jig(board=sink_1_0, layer_thickness=0.4*mm,
-		extrusion_width=0.6*mm, clearance=0.1*mm) {
+		extrusion_width=0.6*mm, clearance=0.35*mm) {
 	/* It would be ridiculous to try to cram enough information into the board
 	 * objects to properly parameterize this, so the board is only used to set
 	 * which object we're making. */