Issue #1024370: Make sure we can use a top level form value $form_state['values']['captcha_response'], even if the form has #tree=true.

Issue #976436 by matheusgorino, soxofaan: Adds an ob_end_clean to prevent the output image from being corrupted.

Issue #1024370 by soxofaan, nineLemon, Pancho, slashrsm: Prevents CAPTCHA from failing in certain forms

removing empty line in the begining of the file I think this was caused by d13f91fa from The Great Git Migration :)

removing empty line in the begining of the file I think this was caused by d13f91fa from The Great Git Migration :)

removing empty line in the begining of the file I think this was caused by d13f91fa from The Great Git Migration :)

#881156 by elachlan and soxofaan: disable autocomplete on CAPTCHA response field with javascript (instead of with non-standard markup)

#825088 by Nedjo and Soxofaan (first part, ported to D7): renamed 'type' column in 'captcha_point' table to 'captcha_type' to make it exportable

#810534: protection against CAPTCHA session reuse attacks, port of http://drupal.org/node/810534#comment-3158926, http://drupal.org/node/995748 and http://drupal.org/node/844148