Deletion changes and chown command

[TheJokr]

Changed deleting to making articles hidden

• The hidden column is used to determine if an article is visible to users. It is 0 (visible) by default
• faq delete will set hidden = 1 (hide it)
• New command faq revert will set hidden = 0 (show it)
• Added faq index [show hidden] to list all entries, including hidden ones
• Changed faq_version to 2
• Added missing help texts
• faq revert will only show non-hidden entries]
• Cleaned up code to be more readable
• VMBot FAQ DB Conversion Script can be used to update the DB from v1 to v2. Make sure to run this before firing up the bot.

  Added faq chown

• faq chown <ID> <new Author> changes ownership of an article to <new Author> in order to let <new Author> edit the document

  Improved Error Messages

• There is a proper error message for missing tables now