Better tuning of superscript/subscript offsets to match algorithm used for plstr code in plsym.c that is used for Hershey fonts (e.g., -dev xwin).
Better tuning of superscript/subscript offsets to match algorithm used
for plstr code in plsym.c that is used for Hershey fonts (e.g., -dev
xwin).

However, there are still at least two superscript/subscript bugs for
the cairo devices.

1. test_superscript_subscript.py results show that the vertical
   offsets for superscripts with -dev xcairo largely match those from
   -dev xwin.  This is expected because it was those offsets I used to
   tune the cairo device driver.  However, the subscript vertical
   offsets are slightly too large in magnitude, i.e., the subscript
   is placed too low compared to the corresponding superscript.
   Off by 1 error for subscripts?
   
2. The plbox axis exponents that occur for badly scaled axis
coordinates are written using plmtex.  I mimic those plmtex calls with
test_superscript_subscript.py.  As expected, the exponent strings from
plbox and test_superscript_subscript.py with -dev xwin have the same
vertical offsets. However, the -dev xcairo results for the two cases
are quite different with the plbox result having much too large a
vertical offset for the superscript.  Starting superscript offset
level is off by 1 for plbox?


svn path=/trunk/; revision=11778

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