Support to add custom labels for csv import

[ramirser000]

Hello,

Can the labels from the files lang/csv2vcard.inc be allowed to be customized?

Similar to how the regular language function works:
$rcube->load_language($_SESSION['language'], null, $texts);
However this function doesn't update the csv mapping labels.

[johndoh]

I have been working simplifying the CSV to vCard mapping process. Currently waiting on #9431

My idea is that, in the end, lang/csv2vcard.inc will contain everything needed for mapping e.g. an entry like $map['email:other'][] = "E-mail 3 Address"; would map the title "E-mail 3 Address" to the Email Other field in Roundcube.

It does not add use of $rcube->load_language() which is not currently part of the process.