Window: Remove NODRAG window property
Such a feature does not exist for windows. To make it undraggable you can
create a borderless (undecorated) window
Window: Create takes a third properties param
Font: Fix annoying warnings
Build: Overhauling SDK build
SDK build now has its own target, which simply copies Bakge and library
headers into the SDK directory. Also did a lot of cleanup on useless build
code. Still a lot of work to do.