t1046: Created springboard_cookie.module, with a basic springboard_cookie_get_cookie() function.
t1046: Removed urlencode() from secure_prepopulate_encrypt() and adjusted af and gs string generators and encryption unit test accordingly. URL encoding is only required for ciphers that will come back to us via query strings, which PHP will URL-decode for us. Other applications (like the Springboard Cookie) will expect secure_prepopulate_decrypt(secure_prepopulate_encrypt('Hello, World!')) to give 'Hello, World!'
t1046: Added springboard_cookie_set_cookie() function and SPRINGBOARD_COOKIE_COOKIE_NAME constant.
t1046: Added Springboard Cookie admin fieldset to Secure Populate settings. Made the cookie name configurable.
t1046: Added hook_init() to springboard_cooking.module to implement autologin when enabled and a Springboard cookie matches an existing user's email.