Changes in SignonIdentity: libsignon-glib Reference Manual

## Changes in SignonIdentity

`signon_identity_store_credentials_with_args()` has been completely removed, only `signon_identity_store_info()` should be used.

`signon_identity_store_credentials_with_info()` has been renamed to `signon_identity_store_info()` as SignonIdentityInfo is the only way to get and set the identity informations.

`signon_identity_add_reference()` and `signon_identity_remove_reference()` have been completely removed without replacement.

The "id" property is now read-only and only settable at construction time. There is a new `signon_identity_get_id()` method to easily get the value of the property. The object now notifies when the property has changed with a property signal emition.

The "signout" signal has been renamed to “signed-out” to be more descriptive and avoid symbol collisions with the `signon_identity_sign_out()` method.

The `signon_identity_signout()` has been renamed to `signon_identity_sign_out()` to avoid symbol collisions with the "signout" signal.

All the methods have been modified to use the GAsyncResult API. Use *_finish() in your GAsyncReadyCallback to get the result of the operation.

`signon_identity_info_get_access_control_list()` and `signon_identity_info_set_access_control_list()` now make use of the new SignonSecurityContext structure that replaces the simple security context string.