Allow the configuration of EPUBCheck’s Locale

[rdeltour]

This PR completes and replaces #650.

The locale used by EPUBCheck can now be configured:

• with a --locale option on the command line
• with the setLocale(Locale locale) method on the EpubCheck class
• when no locale is provided, the library will fall back to the default
  JVM Locale (i.e. EPUBCheck’s behavior doesn’t change)

This PR introduces the following changes:

• Refactored com.adobe.epubcheck.util.Messages:
  • new static getInstance(…) methods to get the Messages instance
    for the given (optional) locale and class name (used to resolve
    the name of the underlying ResourceBundle).
  • the Messages instances are cached in a table, keyed with locale
    codes and resource bundle names.
• Refactored the com.adobe.epubcheck.message package:
  • MessageDictionary is now an interface; it's functionality is split
    in several classes to handle default messages, loading of override
    files, overridden messages, dumping message files, and severities.
  • messages and severities are cached.
• Refactored the org.idpf.epubcheck.util.css package, to make it
  locale-aware:
  • a Locale is given as an argument to the CSSParser constructor
  • the package Messages class is removed, replaced by the main
    com.adobe.epubcheck.util.Messages
• New LocalizedReport interface, extending the Report interface with
  locale getter/setter methods, representing a localizable report.
  • the existing Report interface is kept unchanged, for backwards
    compatibility
  • MasterReport implements this new LocalizedReport interface
  • the localization code checks if the underlying report is an instance
    of LocalizedReport before setting a new locale.
• New LocaleHolder facility to statically store the "current" locale
  in a thread-local variable. This is used by libraries that cannot be
  configured dynamically with a new locale (like Jing).
• Monkey-patch Jing's Localizer class to load Jing's resource bundles
  for the locale exposed in the LocaleHolder utility.
• Expose the current locale in the ValidationContext class
• Update the java sources compatibility version to 1.7
• New locale-related tests

Limitations:

• Jing's localization relies on the locale information exposed in a
  static thread-local variable (in the LocaleHolder class). Any new
  implementations of the LocalizedReport must make sure that the locale
  stored in the LocaleHolder is updated when the locale is changed or
  initialized.
• The validation messages defined in the schematron schemas are still
  not localized.

Thanks to @matthew-macgregor for the original PR contribution (#650)!

Closes #650
Fixes #498

[tofi86]

Just tested these changes with "pagina EPUB-Checker":

• --locale has currently no effect on the --help message, but I think this is acceptable for the moment.
• I pushed a small fix for a unicode glitch in original PR Flexible localization options. #650 (see 91ccd2f)

Everything else works well! 👍

[rdeltour]

thanks for the testing @tofi86!

--locale has currently no effect on the --help message, but I think this is acceptable for the moment.

Mmm, weird, it does work for me… note that currently the --locale option has to be set before the --help option to be taken into account, maybe that's why?

[tofi86]

Mmm, weird, it does work for me…

Sorry, I tried --locale=fr instead of --locale fr yesterday. My fault.

Works fine!