Localization (natural language support)

Previously, the default language for format-date() and related functions in XSLT was taken from the Java default locale. This has been changed so that a non-English language is used as the default only if (a) it is the language of the Java default locale, and (b) there is an installed numberer for that language. The effect of this change is to eliminate the warning output [Language: en] produced when the Java default locale is non-English but there is no localized numberer available for that language.