XAR entry types improvements

Starting XWiki 10.4 we started to introduce the concept of page "Types".

• Several ways to protect extension pages are now provided and can be configured in xwiki.properties:

  #-# The possible choices are:
  #-# * none: no protection at all
  #-# * warning (the default): everyone get a warning when trying to edit a protected document
  #-# * deny = EDIT/DELETE right is denied for everyone except for admins who just get a warning
  #-# * forcedDeny = EDIT/DELETE right is denied for everyone, admins can't force edit/delete
  #-# * denySimple = EDIT/DELETE right is denied for simple users except for simple admins who just get a warning
  #-# * forcedDenySimple = EDIT/DELETE right is denied for all simple users, simple admins can't force edit/delete
  # extension.xar.protection=warning
• Main.WebHome page entry type is now demo since the wiki home page is configurable so there is no reason to prevent its deletion
• XWiki.XWikiAdminGroup page entry type is now configuration, was forgotten in previous version
• the type home has been removed since it was designed for wiki home page use case which does not make much sense anymore