CTools plugin issue

So, I've reported this issue with various modules that use CTools Export UI and dealt with it myself as I write a lot of modules with CTools Export UI integration, but it is a bit of an odd one that I have dug into various times.

Suffice to say, the basics of the issues is that due to caching and ctools use require_once() to load plugin definitions, in some cases a CTools export UI plugin definition is not longer available for use while that plugin is trying to act. More details can be read in my last delving into this issue: #2386819: Encrypt/Decrypt and cache clear issue with CTools plugin system

The simplest resolution, the one I deal with in that issue, is to using HOOK_PLUGIN_ctools_export_ui() to declare the plugins, which is a fairly undocumented function, but it changes nothing one your behalf except for making the CTools export UI plugin more reliable.

Patch incoming.