Test: add missing html tag
Various: Use ES5, users should polyfill on their own for IE8 support

Fixes #244
Fixes #259
Fixes #260
Closes #276
Test: Drop jquery, it's not needed or used

jQuery core is not used as a dependency for tests. It's currently included for
no reason.
Build: Update license

Closes gh-263
Test: Remove invalid leftover comment
Date: Fix hour parsing hKHk

Fixes #277
Various: Create simple internal common message formatting

Ref #265
Minor coding standards fix
Various: Validate parameters presence, type and value

Ref #251
Various: Validate CLDR content

Ref #251
Various: Validate default locale

Validate if default locale has ever been set on any static method call.

Ref #251
README: Create Error reference section

Fixes #251
Various: Revert missing CLDR validation via `{throw: true}`