MI non-stop and multiprocess docs.

	MI non-stop and multiprocess docs.

        * gdb.texinfo (GDB/MI): New section 'GDB/MI General Design'
        (GDB/MI Output Records): New section 'GDB/MI Frame Information'
        Adjust documentation for *stopped, document =thread-created,
        =thread-exited, =thread-group-created and =thread-group-exited.
        (GDB/MI Thread Commands): Document the 'state' field in
        -thread-info output.
        (GDB/MI Program Execution): Mention --all and --thread-group
        options.
        (GDB/MI Variable Objects): Describe floating and fixed variable
        objects.
        (GDB/MI Miscellaneous Commands): Document -list-thread-groups.