Proposal to remove ext files from dev branch

[ajedele]

The external files are generated for each experiment in the unpacker. The external files are used by the reader to map the channels correctly.

The external files are experiment specific and should be generated in the experiment-specific unpacker and should be copied over for each experiment. Otherwise, this leads to potential incorrect mapping or channel numbers/ADC ranges/trigger information. Our naming and mapping changes often enough that this will be an issue.

Since this is in the 1st step of the analysis, most new users will be unaware of the potentially incorrect external files.