mixed mesh support is broken

[cwsmith]

As of cwsmith/phasta@ba1c73e support for reading mixed meshes via syncio is broken in phSolver; the topology type index before the @ symbol is hardcoded to '1'.

/cc @KennethEJansen @mrasquin @matthb2

[cwsmith]

The mixed mesh compressible test case files have been renamed compressibleMixedMesh in www.scorec.rpi.edu/~cwsmith/phastaCases.tar.gz . An all tet case from Ken's colorado dir
/scratch/kjansen/Redo5850-Chef has replaced the compressible files.

[cwsmith]

some notes:
A dependency was introduced at some point on the ordering of file contents and that was the only reason why the '?' approach worked for posix IO. In syncio, that approach does not work as some parts will not have all topologies (there is communication after each?) and integers were added to the phrase strings to uniquely identify each topology and its related fields.