Copy doc comments from Rust to JS (#265)

* backend comments complete

* better matching

* gen comments

* Add example

* Move test bindings gen to own fn

* move build step into build fn

* add fn to read js, refactor gen_bindings/test to allow for this

* Add comments test

* Update readmes

* add comments to travis

* fix broken tests

* +x on build.sh

* fix wbg cmd in build.sh

* Address fitzgen's comments

examples/comments/src/lib.rs

@@ -0,0 +1,60 @@
+#![feature(proc_macro, wasm_custom_section, wasm_import_module)]
+
+extern crate wasm_bindgen;
+
+use wasm_bindgen::prelude::*;
+
+#[wasm_bindgen]
+/// A user defined comment
+pub struct Comment {
+    name: String,
+    comment: String,
+    /// The position this comment
+    /// should exist at
+    pub count: u32,
+    color: Color,
+}
+
+
+#[wasm_bindgen]
+impl Comment {
+    #[wasm_bindgen(method)]
+    /// The name of the user who
+    /// posted this comment
+    pub fn name(&self) -> String {
+        self.name.clone()
+    }
+    #[wasm_bindgen(method)]
+    /// The content of this comment
+    pub fn comment(&self) -> String {
+        self.comment.clone()
+    }
+
+    #[wasm_bindgen(constructor)]
+    pub fn new(name: String, comment: String, count: u32) -> Comment {
+        let color = if count % 2 == 0 {
+            Color::Blue
+        } else {
+            Color::Pink
+        };
+        Comment {
+            name,
+            comment,
+            count,
+            color,
+        }
+    }
+    #[wasm_bindgen(method)]
+    /// What color should this comment be
+    pub fn color(&self) -> Color {
+        self.color.clone()
+    }
+}
+
+/// The border of a comment
+#[wasm_bindgen]
+#[derive(Clone)]
+pub enum Color {
+    Blue,
+    Pink,
+}