This can be used to deallocate isds_pki_credentials structure with safe
password erase.

If desctructor is NULL, it will not be called in isds_list_free().
It it isn't, it will be called regardless data member value.

NULL desctructor can be used to list staticly allocated data.

2010-02-03T05:06:07-01:45

2001-02-03T04:05:06.123456
2001-02-03T04:05:06.123456Z

Negative time zone fails and other test segfaults. God bless tests.

Automake 1.11 brings color test results output. For unknown reason the
color-test automake option must be declared on each directory level.

FIXME: Last test with invalid input fails