The library concepts needs fixing. It is hard to write a library with code that can be reused outside the Arduino world.
The idea of the sketches leaves me puzzeled too. Who came up with the wondrous idea, that any additional file used needs to be copied (<-- no joke ) into the sketch directory? A reusability nightmare!
Who came up with the wondrous idea
This is so broken in so many ways...
Perhaps you should try the AVR Studio C approach and then you won't have to deal with Arduino IDE.
Anyway, the two locations suggested in different places do confuse me.
it would be very helpful to simply implement cooperation with an external editor in a better way.