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)*

docs/design/feature-goals.md

@@ -57,7 +57,7 @@ Contributions welcome! If you think of something Graphite would be great for, su
 - Removing translucent watermarks that were applied in the same location to a batch of photos by finding their shared similarities and differences and using that as a subtraction diff
 
 ## Game development
-- Design a GUI for the game and use the Graphite Renderer Core Library to render the in-game GUI textures at runtime at the desired resolution without scaling problems, or even render it live as data updates its state
+- Design a GUI for the game and use Charcoal to render the in-game GUI textures at runtime at the desired resolution without scaling problems, or even render it live as data updates its state
 - Authoring procedural noise-based textures and PBR materials
 
 ## Data visualization