Improve tag feature #2 : avoid accented characters in tags

[Globulle]

Following issue #6076, a second step to reduce the number of different spellings for tags should be to consider accented characters such as é è ë ê as equivalent to their basic one e because accents are often dropped out (because it's easier or people don't know whether they are permitted or not within tags). This way, if I post something related to, say, ecology in french, I wouldn't need to write both #écologie and #ecologie. I think (but may be wrong) that as such they still make sense in most languages.

[jhass]

I'd like that implemented upstream and not by us if possible.