This allows to give at least some explanation about why the secrets
can't be stored to the user, e.g. they could search for a message such
as
The name org.freedesktop.secrets was not provided by any .service files
to find out that gnome-keyring package needs to be installed on their
system.
Note that this change means that under Unix an attempt to connect to the
secret service is now made when wxSecretStore is constructed and not
just when it's used for the first time, as before.
The old API didn't make any sense for the most common case when both the
user name and password need to be stored, as it required providing the
user name as input, which couldn't work (but somehow this went
unnoticed for more than a year...).
Fix this by returning the username, and not only the password, from
Load() instead of taking it as parameter and removing this parameter
from Delete() as well.
Also improve the documentation, notably include a simple example of
using this class.
Notice that this is a backwards-incompatible change, but the old API was
really badly broken and didn't appear in 3.1.0 yet, so the breakage is
both unavoidable and, hopefully, shouldn't affect much code.
Nevertheless, a special wxHAS_SECRETSTORE_LOAD_USERNAME symbol is added
to allow testing for it if necessary.
Add a new class allowing to store passwords and other sensitive information
using the OS-provided facilities.
Add implementations for all the main platforms, documentation and a new sample
(which contains an ad hoc unit test as the real unit test for this class would
probably be a bad idea as it wouldn't run in non-interactive contexts and
could show OS level dialog boxes if it did).
