Adding support for Parallel distributed MPI based programs

**Is your feature request related to a problem? Please describe.**
Dear cs01 thanks for gdbgui it is a very interesting project. Parallel distribute MPI (Message Passing Intergace) debugger like Allinea DDT or TotalView are very expensive debuggers. DDT, despite being the best. does not support Mac OSX. I am at the moment exploring the possibility to extend gdbgui to work with MPI based programs. The approach is to use multiple remote gdb-servers with 1 GUI controlling by muliple gdb sessions connected to the servers. Here is my fork https://github.com/incardon/gdbgui. My idea is to arrive to a version that I can integrate in our parallel simulation environment to debug parallel distributed programs

**Describe the solution you'd like**
Now is early. But I would like to check if there would be interest in integrating such feature at some point once is finished. And in particular, to discuss the approach I am following and introducing regression tests.

No files, tests, or entry points are named. Start by reviewing the existing gdbgui architecture and the linked fork's multiple-gdb-session approach, then define the integration scope and regression tests needed for MPI-based debugging.

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