Form helpers don't handle "question?" methods

I'm carrying this forward from my Trac ticket (I rebased the changes to the current revision.)

The form helpers currently don't account for boolean question methods correctly (e.g. :secret?), so it outputs the question mark in the tag's name parameter. This patch fixes the name attribute so the returned parameter corresponds with the the right name for the model's setter method.

Currently, this code:

<%= f.check_box :secret? %>

Produces the following input tag:

<input name="post[secret?]" ... />

In fact, it should produce the following, so that the returned parameter can be directly assigned as :secret=, not :secret?=

<input name="post[secret]" ... />

This would be the expected behaviour for direct assignment back into the model using AR::Base.new, update_attributes, etc...

def create
  Post.new( params )

  # Currently have to work around the above mass assignment using:
  # secret = params.delete(:secret?)
  # Post.new( params )
  # Post.secret = secret
end