Make size/position types generic over pixel type (#1277)

* Begin implementing DPI generics

* Fix multithreaded example

* Format

* Fix serde test

* hopefully fix most of the errors

* Fix dpi module errors

* More error fixings

* Format

* fix macos errors

* Another error pass

* Replace bad type signatures

* more fixins

src/platform_impl/web/web_sys/canvas.rs

@@ -94,7 +94,7 @@ impl Canvas {
         self.raw.height() as f64
     }
 
-    pub fn set_size(&self, size: LogicalSize) {
+    pub fn set_size(&self, size: LogicalSize<f64>) {
         self.raw.set_width(size.width as u32);
         self.raw.set_height(size.height as u32);
     }

src/platform_impl/web/web_sys/event.rs

@@ -22,7 +22,7 @@ pub fn mouse_modifiers(event: &MouseEvent) -> ModifiersState {
     m
 }
 
-pub fn mouse_position(event: &MouseEvent) -> LogicalPosition {
+pub fn mouse_position(event: &MouseEvent) -> LogicalPosition<f64> {
     LogicalPosition {
         x: event.offset_x() as f64,
         y: event.offset_y() as f64,

src/platform_impl/web/web_sys/mod.rs

@@ -40,7 +40,7 @@ impl WindowExtWebSys for Window {
     }
 }
 
-pub fn window_size() -> LogicalSize {
+pub fn window_size() -> LogicalSize<f64> {
     let window = web_sys::window().expect("Failed to obtain window");
     let width = window
         .inner_width()