Expose `__parse()` static private method
Throw in constructor if there is no valid `pattern` argument
Fix bug referencing undefined `NumberPart` helper class, it was removed
Remove offset logic and NumberPart. Remove custom type case.
Merge branch 'perf' of github.com:ericf/intl-messageformat into perf
Rename _buildFormatPattern() to _compilePattern()
Ensure parse returns an array if it is a string.
Merge branch 'perf' of github.com:ericf/intl-messageformat into perf
Update tests