modify gmv IO tests to ascii output

[daniellivingston]

gmv binary files are different on every platform and OS types.
test only ascii versions of gmv files

[millerta]

addmesh_add() hard-wired to dump gmv polygon.gmv and polygon.inp
I removed dump/gmv, and left dump/avs
Need to figure out what this file is and why it is written. It is not described in code or documentation.
Note all coordinates in polygon.inp are 0. 0. 0. and newer avs file writes integer instead of real attributes.
I will replace reference with the newer version with integer values

tail polygon.inp
   4000  2  0  0  0
   4001  2  0  0  0
   4002  2  0  0  0
tail reference/polygon.inp
0000004000  2.000000000000E+00  0.000000000000E+00  0.000000000000E+00  0.000000000000E+00
0000004001  2.000000000000E+00  0.000000000000E+00  0.000000000000E+00  0.000000000000E+00
0000004002  2.000000000000E+00  0.000000000000E+00  0.000000000000E+00  0.000000000000E+00