Added Postscript outout for measurements, plus assorted changes.

- postscript.c: added patterns backhatchpath and crosspath (for pad overlaid 
  with solder paste)
- postscript.c: added measurements
- postscript.c: prefixed style parameters with PS_ to avoid future conflicts
  with gui_style.h
- when changing the default unit, we now cancel the selection, and refresh 
  canvas and current position
- on-screen measurements now suppress the unit if set to anything but "auto"
- use  __attribute__((format(printf, ...))) for printf-like functions
- the unit selector now has a white background to make it clearer that it can 
  be clicked



git-svn-id: http://svn.openmoko.org/trunk/eda/fped@5461 99fdad57-331a-0410-800a-d7fa5415bdb3

TODO

@@ -21,6 +21,10 @@ Style:
 - status area looks awful
 - add button with GTK_STOCK_UNDELETE for "undelete" to menu bar
 - edit names/values/etc. in place if possible
+- maximizing pad name size creates uneven text sizes. Particularly "1" gets
+  excessively large.
+- pango_layout_get_size doesn't seem to consider rotation, so we currently
+  don't properly size rotated text.
 
 Bugs:
 - default silk width has no business being hard-coded in obj.c