Restructure project directories (#333)

`/client/web` -> `/frontend`
`/client/cli` -> *delete for now*
`/client/native` -> *delete for now*
`/core/editor` -> `/editor`
`/core/document` -> `/graphene`
`/core/renderer` -> `/charcoal`
`/core/proc-macro` -> `/proc-macros` *(now plural)*

editor/src/input/mouse.rs

@@ -0,0 +1,62 @@
+use bitflags::bitflags;
+use glam::DVec2;
+
+// origin is top left
+pub type ViewportPosition = glam::UVec2;
+
+#[derive(Debug, Copy, Clone, Default, Eq, PartialEq, Hash)]
+pub struct ScrollDelta {
+	pub x: i32,
+	pub y: i32,
+	pub z: i32,
+}
+impl ScrollDelta {
+	pub fn new(x: i32, y: i32, z: i32) -> ScrollDelta {
+		ScrollDelta { x, y, z }
+	}
+	pub fn as_dvec2(&self) -> DVec2 {
+		DVec2::new(self.x as f64, self.y as f64)
+	}
+	pub fn scroll_delta(&self) -> f64 {
+		let (dx, dy) = (self.x, self.y);
+		dy.signum() as f64 * ((dy * dy + i32::min(dy.abs(), dx.abs()).pow(2)) as f64).sqrt()
+	}
+}
+
+#[derive(Debug, Copy, Clone, Default, Eq, PartialEq, Hash)]
+pub struct MouseState {
+	pub position: ViewportPosition,
+	pub mouse_keys: MouseKeys,
+	pub scroll_delta: ScrollDelta,
+}
+
+impl MouseState {
+	pub fn new() -> MouseState {
+		Self::default()
+	}
+
+	pub fn from_pos(x: u32, y: u32) -> MouseState {
+		MouseState {
+			position: (x, y).into(),
+			mouse_keys: MouseKeys::default(),
+			scroll_delta: ScrollDelta::default(),
+		}
+	}
+	pub fn from_u8_pos(keys: u8, position: ViewportPosition) -> Self {
+		let mouse_keys = MouseKeys::from_bits(keys).expect("invalid modifier keys");
+		Self {
+			position,
+			mouse_keys,
+			scroll_delta: ScrollDelta::default(),
+		}
+	}
+}
+bitflags! {
+	#[derive(Default)]
+	#[repr(transparent)]
+	pub struct MouseKeys: u8 {
+		const LEFT   = 0b0000_0001;
+		const RIGHT  = 0b0000_0010;
+		const MIDDLE = 0b0000_0100;
+	}
+}