Major Upgrades

I needed functionality to have my lists and custom fields as choices in the block. This patch allows custom fields to be created in the admin interface. It supports radio buttons, select fields, and checkboxes.

It would be great if someone could check it out and give me feedback.

Also, please create a mailbuild.js file with the following code (I wasn't sure how to submit a new file in an issue):

jQuery(function() {
	var $ = jQuery; // Scope jQuery as $
	var last = {el: null, len: 0};
	$('#edit-mblists div:first').children('.form-item')
		.each(function() {
			var fields = $('~ .form-field:first', this), 
				len = fields.find(':input').size();
			$(':radio:first', this).bind('click', function() {
				// Dont animate if last el was me
				if (last.el && (last.el == fields))
					return;
				// Slide up last element
				if (last.el && last.len)
					last.el.slideUp();
				// Update last element
				last = {
					el: fields,
					len: len// leave last comma off
				};
				// Animate me
				// Only do animation if has children
				if (last.el && last.len)
					last.el.slideDown('slow');
			});
			fields.hide();
		}).end()
		// Find first radio and click it
		.find('.form-item:first :radio').click();
});