Improved error handling.
Beautifications:
Added handling of Wavefront keyword "Ni" (Index of refraction). Otherwise "Ni" did overwrite "Ns" specifications.
Released version 2.1.2 on 2026/09/06
Replaced obsolete "www.tcl.tk" with "www.tcl-lang.org".
Corrected out-dated links to photo man page and FLIR specification.
Documentaion updates for upcoming 2.1.2 release.
Updated Img version and copyright date.