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)*

frontend/src/utilities/math.ts

@@ -0,0 +1,3 @@
+export function clamp(value: number, min = 0, max = 1) {
+	return Math.max(min, Math.min(value, max));
+}