Facility to load dynamic libraries

[Mario]

There is no reason for additional loaders,  you can just use char array and loadFromMemory or create image from pixels.
There is also no type safety at all, so there is no (sane) way to do this:

initfuncsig init = plugin.getFunction("init");

But this should be possible:

initfuncsig init = plugin.getFunction<initfuncsig>("init");

There's no real difference, considering no matter what, you'll get a void pointer that you have to cast. Whether you do that inside our outside your retrieval function doesn't matter.

[Laurent]

Yes, but your code had no cast at all

And since this particular cast has to be ugly, it's better hidden inside the function anyway.

[Mario]

Okay, let's use T sf::BrownPaperBag.use<T>(const sf::string &name) then.