Change asciifolding to icu_folding
Rename unidecode function to uni_fold
Remove all marks with stringHelper

- Using proper regexp from xregexp
- Renamed unidecode to uniFold

Thanks for @nickstenning
Move streamer test to h/test
Remove normalization parameter from uniFold
Simplify too complex function in streamer.py

FilterHandler.evaluate_clause had a case_sensitive remnant, removed
FilterToElasticFilter.conver_clauses was dissected by es query_types
Add more tests for stringHelper