Fixes usages of String#toLowerCase() without a Locale.

Replaces #toLowerCase() with #toLowerCase(Locale), #equalsIgnoreCase(String), #compareToIgnoreCase(String), or #regionMatches(boolean, int, String, int, int). #toLowerCase() without a Locale may lead to unexpected results in JVM with Turkish locale (s. JavaDocs of String#toLowerCase()). Additionally it improves performance as #equalsIgnoreCase(), #compareToIgnoreCase() and #regionMatches() are faster in comparison to equivalent code which uses combination of #toLowerCase() and #equals(), #compareTo() or #startWith().