Add plumbing for event system (#52)

* Add plumbing for event system

* Apply review suggestions

* Add swap and reset color functions

Cargo.lock

@@ -1,5 +1,17 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
+[[package]]
+name = "arrayvec"
+version = "0.5.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "23b62fc65de8e4e7f52534fb52b0f3ed04746ae267519eef2a83941e8085068b"
+
+[[package]]
+name = "bitflags"
+version = "1.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cf1de2fe8c75bc145a2f577add951f8134889b4795d47466a54a5c846d691693"
+
 [[package]]
 name = "bumpalo"
 version = "3.6.1"
@@ -35,11 +47,17 @@ version = "0.1.0"
 [[package]]
 name = "graphite-document-core"
 version = "0.1.0"
+dependencies = [
+ "kurbo",
+ "svg_fmt",
+]
 
 [[package]]
 name = "graphite-editor-core"
 version = "0.1.0"
 dependencies = [
+ "bitflags",
+ "graphite-document-core",
  "log",
 ]
 
@@ -66,6 +84,15 @@ dependencies = [
  "wasm-bindgen",
 ]
 
+[[package]]
+name = "kurbo"
+version = "0.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "eb348d766edbac91ba1eb83020d96f4f8867924d194393083c15a51f185e6a82"
+dependencies = [
+ "arrayvec",
+]
+
 [[package]]
 name = "lazy_static"
 version = "1.4.0"
@@ -105,6 +132,12 @@ version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ea6a9290e3c9cf0f18145ef7ffa62d68ee0bf5fcd651017e586dc7fd5da448c2"
 
+[[package]]
+name = "svg_fmt"
+version = "0.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8fb1df15f412ee2e9dfc1c504260fa695c1c3f10fe9f4a6ee2d2184d7d6450e2"
+
 [[package]]
 name = "syn"
 version = "1.0.64"