I've got it!!!!!! I AM THE HAPPIEST PERSON ON EARTH RIGHT NOW!!!!!!!!

Assembly HAS TO BE COPIED to Photoshop folder for some reason. Everything else stays the same!!!! Even full name reference like this
#using <C:\Users\Bogdan\Desktop\ColorPickerControl.dll>

I would like to ask if anybody knows why is this so, and why .net assemblies do not need to be in Photoshop folder?

I couldn't believe when it loaded. I couldn't. Really.
Oh how happy I am right now!