Dragging! & basic proportional box resize frm cursor distance to box pos

Still need to add resize via 'pulling' to stretch the box out from a side or 2 sides diagonally.

Also some general clenaup of code

code/math.odin

@@ -33,6 +33,19 @@ Range2 :: struct #raw_union{
 	},
 }
 
+range2 :: #force_inline proc "contextless" ( a, b : Vec2 ) -> Range2 {
+	result := Range2 { pts = { a, b } }
+	return result
+}
+
 Rect :: struct {
 	top_left, bottom_right : Vec2
 }
+
+add_range2 :: #force_inline proc "contextless" ( a, b : Range2 ) -> Range2 {
+	result := Range2 { pts = {
+		a.p0 + b.p0,
+		a.p1 + b.p1,
+	}}
+	return result
+}