document requirements for TIFF files

It seems, many different kinds of TIFF are generated at instruments worldwide, and not all of them can be read by BornAgain.

• In the webdocs, describe requirements for TFF files to be read, and recommend conversion tools. Also invite users to send us samples of not yet supported TIFF files.
• In the GUI code, upon failure to read TIFF file, print message with link to the docs.

added docs label

assigned to @a.nejati

unassigned @a.nejati

mentioned in merge request !1784 (merged)

mentioned in commit f0b60a3c

closed

reopened

changed the description

mentioned in commit d4f7dc0a

assigned to @m.svechnikov

mentioned in merge request !1836 (merged)

mentioned in commit 014ec0e4

closed with merge request !1836 (merged)

marked the checklist item In the GUI code, upon failure to read TIFF file, print message with link to the docs. as completed