Geomentry fix and preserve argv change

* 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.  The other args are saved for all tabs, which may or
  may not be desired in the case of

    urxvt -pe tabbedex -e <some command>