Geomentry fix and preserve argv options

* Work around one or more bugs in urxvt V 9.12 which cause tabbed
  terminals to open up too small and to ignore X geometry
  resources.  These changes work for me with these choices:

    fvwm2, Slackware64 13.37, my modified (narrowed) NeXT scrollbars.

  I've tried a few other fonts, but the testing wasn't extensive.
  For other scrollbar widths, you need to modify a paramter; see
  the comments at the beginning of on_resize_all_windows().  Also,
  I used some mystery offsets that worked for me.  YMMV.  (See the
  comments and 5 and 27.)  NOTE: these changes work in 9.14 with
  either of the patches suggested on 2011/01/05 on the rxvt-unicode
  mailing list.  NOTE: these changes work in 9.15 with no patches
  applied.

* The previous version of on_start() threw away all of @argv up to
  the "-e" (if it exists).  This tossed away arguments that I want,
  most notably "-ls" and "-e <some command>.  The code below
  passes through everything except "-pe <arg>" and geometry.  If
  other options are found to be problematic they will need to be
  tossed too.