Rename centrage to normalize
Create and test function charsetFilter, which translate int into charset id (-1 when the val is not in the charset)
Remake function first and last letter to normalize them
Merge branch 'master' of https://github.com/darzul/RDNtweet
Add frqPrevLastLetter in parser.c
The training base doesn't count tweet with no char
Recode parser.sh