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/Cargo.toml

@@ -0,0 +1,24 @@
+[package]
+name = "graphite-editor"
+version = "0.1.0"
+authors = ["Graphite Authors <contact@graphite.design>"]
+edition = "2018"
+readme = "../README.md"
+homepage = "https://www.graphite.design"
+repository = "https://github.com/GraphiteEditor/Graphite"
+license = "Apache-2.0"
+
+[dependencies]
+log = "0.4"
+bitflags = "1.2.1"
+thiserror = "1.0.24"
+serde = { version = "1.0", features = ["derive"] }
+graphite-proc-macros = { path = "../proc-macros" }
+glam = { version="0.17", features = ["serde"] }
+
+[dependencies.graphene]
+path = "../graphene"
+package = "graphite-graphene"
+
+[dev-dependencies]
+env_logger = "0.8.4"