Fix LTR/RTL handling in Language::FromLanguageTag
Fix LTR/RTL handling in Language::FromLanguageTag

FromLanguageTag() didn't correctly set m_direction value.

Observable effect was that text alignment was incorrect for XLIFF files
(which use this function), but not for PO files (which use TryParse).

Fixes #724.

nawawi/poedit,PKRoma/poedit,vslavik/poedit,PKRoma/poedit,nawawi/poedit,alexhenrie/poedit,vslavik/poedit,alexhenrie/poedit,alexhenrie/poedit,PKRoma/poedit,nawawi/poedit,PKRoma/poedit,vslavik/poedit,PKRoma/poedit,alexhenrie/poedit,vslavik/poedit,nawawi/poedit,alexhenrie/poedit,vslavik/poedit,nawawi/poedit