Add handlebars form helpers

[nightsh]

Form helpers are a great improvement of the development process. Even more, they centralize the form generation into the helper definition(s), so one can make uniform changes app-wide without having to tinker with every form inside it (at least, not one by one).

Thing is, there are many helpers and bundles of helpers, with or without validation, some incomplete, some obsolete... a review needs to be done, then re-implement the existing forms using the newly chosen helpers.

Thanks in advance to whoever will do this :-)