New functions for sslinfo extension

1) ssl_get_count_of_extensions() --- get count of X509v3 extensions from client certificate;

2) ssl_get_extension_names() --- get short names of X509v3 extensions from client certificate;

3) ssl_get_extension_value(text) --- get value of extension from certificate (argument --- short name of extension);

4) ssl_is_critical_extension(text) --- returns true, if extension is critical and false, if is not (argument --- short name of extension).