Version 1.0.05: Add captcha and possibility to make new proposal with a title

Meeting Schedule version 1.0.05

• Add the possibility to make new proposal in the front-end with only a title (no date).
  This may for example give the possiblity to propose several meeting subject (or themes) for which the people can vote.
• Add the possibility to have a captcha when adding a new attendee or a new proposal.
  The objective is to reduce the risk that robots create fake attendee or proposal when anonymous is allowed.
• Add a "Check DB" in the about menu to allow verifying the DB structure of the Meeting Schedule.
• Fix email list notification.
  When emails were separated by a semi column (;) an error message was reported that the "email" was missing.
  The error was due to a cleanup of the email that is used to verify that it has a good shape.
• Add a cache on email sent to verify and avoid that duplicate email are sent.
• Fix compatibility with Joomla 3.4