fix bug with subset in get_array()

See merge request !230

These are the cumulative changes from said proposal. I left out the changes to load the tunnel XGM, as it was commented out later anyways, and probably should be done different anyways.

See merge request !224

that was a quick hack that should not be done, background subtraction is
the way to go.

Fix min distance in peak finding algorithm

See merge request !227

Undulator configuration

See merge request !225

Only use `select_trains()` when necessary

Closes #64

See merge request !226

See merge request !223

Add mono_order mnemonic

See merge request !217

More mnemonics

See merge request !222

Fix autoapi generation

Closes #23

See merge request !221

Run control values

Closes #63

See merge request !220