#157 TRCIO fails with SEG Y format 5

[seismick]

If a SEG Y file was written in format 5 (IEEE 32-bit float), then the result is garbage. SEG Y was originally big endian. However that did not stop people writing in little-endian format (as with x86 CPUs). The code in segy.f90 tries to guess the byte order and swap when needed, but this logic seems to fail with SEG Y format 5. Comments in the code have format 5 as "IEEE Landmark SEG Y". Perhaps that was big-endian. So extra if clauses migh be needed in segy.f90 or trcio.f90 to correct the issue. cbyt trace viewer also suffers from same problem with SEG Y format 5.