Hm, I know it is a late response after 2 Years. But it is better then nothing.
Maybe the thread starter will see it one day.
A Editor "all in one solution" would be awsome. Fans and Modders would love it, not only for Eaw, but for any other Game aswell.
But only few game communitys do actually have such SDKs becouse many companies like to keep theyr Game Engins and Development tools secret for themselves.
However, in fact there is no "all in one game devellopment solution".
Even the big Game Companies on the Market are using a combination of different tools to create theyr games.
For example : Photoshop for the Textures, 3DSMax or Maya for the Modelling and after that a SDK for the actual Game.
I think it would be possible to devellop such a easy to use, all in one Tool for everyone - but that would take a lot of money/time and skilled programmers.
So you probably have to make your modders/devellopers homework ( that means to learn all that complicated stuff ), or you better dont touch it at all.
--- And sorry for bad spelling, i'm no native English speaker XD