Feature request: Combine multiple recordings

[nagyrobi]

I see that the program combines measurements when the robot passes over the same places, and it appears that precision is higher in these locations.

It would be nice to be able to combine recording files saved from the same area. Something like open a file, and then append file from a previous day etc. and combine the results.

I tried to copy the contents of the measurements json key into one file, program doesn't error out but the displayed data is likely incorrect. I assume some calculations or probably some interlacing is needed between the points...