[New: openFATE 308476] Make text cell interpretation configurable

Feature added by: Kohei Yoshida (kohei_yoshida) Feature #308476, revision 1 Title: Make text cell interpretation configurable Requested by: Kohei Yoshida (kohei_yoshida) Description: For xls compatibility reasons, we modify the formula calculation so that * text cells in an addition throw an error e.g. =A1+B1 where B1 is a text cell. * text cells in SUM are interpreted as 0 e.g. =SUM(A1:B1) where B1 is a text ell. But some users don't like these behaviors since they are "inconsistent" with each other. We probably therefore make these configurable, perhaps in the 'Formula' option page. -- openSUSE Feature: https://features.opensuse.org/308476