* do not use stopwords in fulltext search
apparentyl there is a bug in innodb where including stopwords in a search causes the lookup to fail entirely.
e.g. innodb_ft_enable_stopword must be disabled when the index is edited (rows are added/removed)
* don't create a MATCH AGAINST search from empty search strings after sanitization
* drop fulltext indizes for locale zhCN
logographic languages need special treatment, which handling may differ by db provider
* use LIKE search by default for locale zhCN. Added config option to use fulltext if supported by db.
