I made this ages ago, and I was planning to make an editor for it as well (I do have the code of a semi-completed editor, but it uses BGUI 1) but never got round to finishing it. This is pretty much completed, it works fine like a finished app (not really an app), although I may have taken it slightly further if I had stayed interested in it.
The engine has basic particle functions, like creating an effect and particles for it, you can also create several layers to a particle effect (really just individual effects stuck together so you can manuver them with one command). You can fade, ghost, colour, rotate, move, scale, texture, and do a load of other stuff that you can do with regular objects.
The system is really very simple, so if someone wanted to add another function to do something to the particles, or even edit the current functionality, it'd be very simple. The bulk of the code is just functions that manipulate variables, so you can delete most of them and just manipulate the values manually if you want to make the stuff compile faster.
An example is included in the code, and the commented code is what made the saved particle file (you can save and load effects if you want).
Give credit if you use it in your code
.
Isn't it? Wasn't it? Marvellous!