Ignore accents when matching for the Vomnibar

Derived from #862, this matches URLs/titles containing accents when the search terms contain none, and ignores any accents in the search terms.
This statement escapes special characters in regular expressions (which are matched by `@escapeRegExp`).
I've already moved this into a library function in #1086; merging that PR should change this line to
```regexpString = Utils.escapeRegexSpecialChars string```, which hopefully is clearer.