Support for Intel's MPI debugging

When starting gdb from intel's `mpirun` using:
```
mpirun -gdb -gdb-args --interpreter=mi3 -n 2 ./my-prog
```
output has an leading indicator of which processes are being debugged, for example:
```
[0,1] (mpigdb) run
```
which breaks the output parsing. By proxying the `gdbmiparser.parse_response` I can easily restore the structured output:
```python
mpigdb_prefix = re.compile(r"^\s*(\(mpigdb\))?\s*\[[0-9,]+\]\s")
parse = gdbmiparser.parse_response

def new_parse(a0, *args, **kwargs):
newa0 = mpigdb_prefix.sub("", a0)
return parse(newa0, *args, **kwargs)

gdbmiparser.parse_response = new_parse
```
But the mpi rank information is lost. It would be nice if such information could be included in the parsed output.