bending cathode bug fix + imaging related

What's Changed

• add protections for xregion configuration by @wenqiang-gu in #349
• add plane-to-layer conversion (sync'ed with OmnibusSigProc) by @wenqiang-gu in #335
• Towards imaging with DNN and from artROOT by @HaiwangYu in #350

Simple test:
wirecell 0.29.2.pdf

Full Changelog: 0.29.1...0.29.2