Following a request by Günter, we consider the document fonts (only rm
for now) when selecting an appropriate font encoding.
See #9741
The new default font encoding setting "auto" does
* consider the font encoding needed by the language(s), which can now
have fallback alternatives
* Consider which font encoding is provided by the document font
Thus, cm now will result in OT1 fontenc, if the language can deal with
that.
The font_enc pref is ditched: it is no longer needed.
The automatism is still very basic and is subject to extension.
File format and prefs format change.