Correction for PHP versions without MB support

Hasn't been tested for regressions on a system with MB support but should work fine (to be tested before accepting @jsicot if you have time !)
More information on ExtractOCR combination
Correcting ordering function
Merge remote-tracking branch 'symac/patch-3'
Merge remote-tracking branch 'symac/patch-4'
Merge remote-tracking branch 'symac/patch-5'
Fixed names of non-pages (covers, titles...) and cleaned structure of libraries.
Added translation of javascript strings.