MarCCD::CanRead and SMV::CanRead read the first plausible file of a
directory outside their own try, and the CLI made all three CanRead
calls outside the try that reports a bad input. "rugnux <dir>" whose
alphabetically-first plausible file is unreadable therefore terminated
with no message. CanRead now answers false for anything it cannot read,
and the CLI asks the question where it can report the answer.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013nW6FNRP1bBJJ8pfHiByAT
* Rugnux: basic support for CCD images (marCCD, SMV) and for gzipped miniCBF.
* `jfjoch_viewer`: opens the CCD formats, and fixes to the dataset plots.
* Documentation updates.
Reviewed-on: #81
Co-authored-by: Filip Leonarski <filip.leonarski@psi.ch>