Update 'hu', and flip formal and informal

[smileyhead]

I am opening this PR to update the Hungarian translation, as well as to update the language structure to upstream changes in DokuWiki (dokuwiki/dokuwiki#4509).

The summary of my changes is as follows:

• Updated Hungarian translation ('hu')
• Renamed 'hu' to 'hu-formal' and created a new (informal) 'hu' translation. (Hungarian software generally defaults to informal.)
• Copied the English language file's structure and comments to the Hungarian one.

The following changes have been made to translation wording/quality:

• Removed some oddities, such as:
  • The plugin referring to itself in first person (‘I could not…’ → ‘…has failed’);
  • the plugin referring to the install as its own (‘Our DokuWiki install’ → ‘The DokuWiki install’).
• Removed grammatically incorrect hyphenated suffixes (‘DokuWiki-t’ → ‘DokuWikit’).