Revert "Don't disaply empty windows on ctrl-c by pyplot"

This reverts commit 1a8d23b82b35564bcc1d36ad21fd527e8a6bfec8.
Allow not separating scans in experiments
Check experiment iteration only once by creation
Log parameter access only once
Allow walker to be None in experiments
Make forced plotting optional for coroutine case
Merge pull request #345 from ufo-kit/beamtime-fixes

Beamtime fixes