Provide utilities for convenient plotting of channels

Implement a set of utilities (along with basic examples) to
make it so that we can readily make plots of individual channels
from logfiles (or live on the robot).

Change-Id: Ic648c9ccb9dcb73419dc2c8c4c395fdea0536110
diff --git a/aos/network/www/config_handler.ts b/aos/network/www/config_handler.ts
index df2d4f8..73b6b89 100644
--- a/aos/network/www/config_handler.ts
+++ b/aos/network/www/config_handler.ts
@@ -72,14 +72,8 @@
       const channel = this.config.channels(Number(index));
       this.connection.addHandler(
           channel.name(), channel.type(), (data, time) => {
-            const config = this.connection.getConfig();
-            let schema = null;
-            for (let ii = 0; ii < config.channelsLength(); ++ii) {
-              if (config.channels(ii).type() === channel.type()) {
-                schema = config.channels(ii).schema();
-              }
-            }
-            const parser = new Parser(schema);
+            const parser =
+                new Parser(this.connection.getSchema(channel.type()));
             console.log(
                 parser.toObject(Table.getRootTable(new ByteBuffer(data))));
           });