add offset / scrolling + clipboard support

src/core/mod.rs

@@ -1,7 +1,9 @@
 mod align;
 mod image;
+mod offset;
 mod pad;
 mod rect;
+mod scroll;
 mod sense;
 mod sized;
 mod span;
@@ -12,8 +14,10 @@ mod trait_fns;
 
 pub use align::*;
 pub use image::*;
+pub use offset::*;
 pub use pad::*;
 pub use rect::*;
+pub use scroll::*;
 pub use sense::*;
 pub use sized::*;
 pub use span::*;