TimeExpressionParser : removing accents before treatment

TimeExpressionParser : removing accents before treatment (allowing easier treatment for french words as "siècle" in
Replacing AEC (BCE translation) by av. J.-C. (BC translation), expending centuryIndicator and rangeConjunctions

Replacing AEC (BCE translation) by av. J.-C. (BC translation) as it is still way more frequent in France for now
Expending centuryIndicator
Expending rangeConjunctions
Merge pull request #12 from ideesculture/timeexpressionparser

Timeexpressionparser : removing accents before treatment, minor corrections to fr_FR.lang