WebComment: improve comment reply handling
WebComment: improve comment reply handling

* When displaying the editor to submit a reply, use a markup that will
  let users insert inline comments in the quoted replies. This is done
  by using a block for each line instead of a single <div> for the complete
  quotation.

* Use <blockquote> tags instead of <div class="commentbox">
  blocks, which are closer to how FCKeditor manage quotations (enabling
  users to insert standard quotes using the quotation button of the
  toolbar). Added style so that both techniques look the same.

* Improve washing of input comments so that they look better when
  used as reply in cases where FCKeditor cannot be loaded.

* Improve washing of comments sent via email to subscribers (HTML ->
  text conversion).

* Add new 'indent_block' parameter to function
  webmessage_mailutils.email_quoted_txt2html() to allow insertion
  of indentation markup at each line or each change of level of
  indentation.
  Add corresponding unit test.

* "Double-escape" input for the editor in order to correctly
  preserve the markup.

inveniosoftware/invenio-base,inveniosoftware/invenio-base,tiborsimko/invenio-base,tiborsimko/invenio-base