Mask object

This MR adds a mask object that handles all chip masks as well as mask shifting. It replaces scan_base.prepare_injection_masks() with an iterator that is called from the scan loop. This should make mask handling and updating a lot more readable and understandable.

Potential speedups in mask writing have been implemented and initial benchmarks show a gain in total runtimes of digital and analog scans of about 2s. Caching of mask steps for multi-loop scans has been implemented. Threshold scans are now faster than development.

This MR fixes #154 (closed), #255 (closed), #254 (closed), #266 (closed)

TODO:

• fix #230 (closed) by implementing a completely new crosstalk scan with 8 different injection patterns that depends on the mask object
• speedup threshold_scan if possible
• implement new tuning algorithm and deprecate meta_tuning
• test remaining scans
  • Fix stuck pixel scan
  • Fix fast threshold scan
  • Fix noise tuning
  • Fix ToT tuning
• Implement injection delay mask as another mask
• Increase low threshold performance of new TDAC tuning if possible (moved to open issue #269 (closed))