Provide a Locale API for QML similar to QLocale

The javascript parse function doesn't handle some aspects of localized integer representations such as group separators, which is inconsistent with Qt's integer parsing and validation. Specifically IntValidator will accept strings which be won't fully parsed using parseInt().

Exposing QLocale's string parsing and formatting functions in QML would provide capabilities consistent with what is already available in C++.

There are similar requirements for access to other APIs of QLocale, for example the measurement system and currency formatting. The entire QLocale API is also required in QML.