Modules: grapher layout and file export fixed for Windows

[stephendade]

Fixed two issues with MAVExplorer graphs not working nicely:

• Changed to "TkAgg" backend on Windows, as the "wxAgg" backend wasn't displaying the chart values (lower right) correctly
• When saving graphs to file ("save" icon on graph window), made the suggested filename safer by removing problematic characters (ie Sensors/GPS/GPS Accuracy to Sensors_GPS_GPS_Accuracy)

[peterbarker]

@MichelleRos this seems to say that graphing works for Stephen; could you test this PR to see if graphing actually works for you after this, please?

[MichelleRos]

Just tested it. Graphing seems to be working, and the save icon does work on the "canned" graphs I tested, but when I tried just graphing something from the command line it threw this error and didn't bring up the dialog box:

Exception in Tkinter callback Traceback (most recent call last): File "tkinter\__init__.py", line 1921, in __call__ File "matplotlib\backends\_backend_tk.py", line 858, in save_figure File "MAVProxy\modules\lib\grapher.py", line 293, in <lambda> TypeError: 'NoneType' object is not iterable

Note that I've been using MAVExplorer via WSL rather than using the Windows one, so I don't know what did or didn't work before. 😅

(Though on MAVExplorer via WSL I don't think the save icon has ever worked for me. I've just been using a screenshot app when I want to get an image of a graph.)

[stephendade]

Just tested it. Graphing seems to be working, and the save icon does work on the "canned" graphs I tested, but when I tried just graphing something from the command line it threw this error and didn't bring up the dialog box:

That's now been fixed.

I also added a few more fixes based upon https://discuss.ardupilot.org/t/mavproxy-version-in-windows/121556/10?u=stephendade:

• Heli param definitions now included in build
• Fixed up another graphing issue in Windows (magfit in MAVExplorer)
• Modernised the Windows build scripts