Better leverage the power of GDB

[stevenj]

Enhancement requests:

1. It would be nice if the debugger used the python enabled version of gdb arm-none-eabi-gdb-py because its a lot easier to write scripts and extended functionality, which is useful for embedded system debugging. In the event that the -py version isn't found, fall back to the non -py version.
2. A feature to allow a window, to executes an arbitrary gdb command and displays the output when the target halts. (Like the memory window, but running any arbitrary command).

Rationale: I work around 1 myself by copying away the non-python version of gdb and symlinking that name to the python version. It works fine. I need to do this because i want to interrogate the Micro Trace Buffer and that's already implemented for GDB as a Python script. See gdb-micro-trace-buffer. Which I run manually in the debug console. It would be nice, when I want to use it, to open a window which runs that script every time the target breaks and displays it's output. Hence, enhancement request 2.