Rework to split layer generation and triangle rendering.

Cargo.lock

@@ -145,6 +145,8 @@ version = "0.1.0"
 dependencies = [
  "approx",
  "clap",
+ "serde",
+ "serde_derive",
  "stl_io",
 ]
 
@@ -175,6 +177,26 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[package]]
+name = "serde"
+version = "1.0.203"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7253ab4de971e72fb7be983802300c30b5a7f0c2e56fab8abfc6a214307c0094"
+dependencies = [
+ "serde_derive",
+]
+
+[[package]]
+name = "serde_derive"
+version = "1.0.203"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "500cbc0ebeb6f46627f50f3f5811ccf6bf00643be300b4c3eabc0ef55dc5b5ba"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "stl_io"
 version = "0.7.0"