Update renderer to use readline parser and tagged serial data

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Also sets the style of the bars to fill up the screen space, though it could probably be done a little better using flexbox or something.

It also sets the baud rate to 115200 because 9600 isn't fast enough to keep up.

The arduino firmware will end up needing these changes to match:

# serial.h

void printValues() {
+ Serial.print("v");
  for (int i = 0; i < NUM_STEPS; i++) {
    Serial.print(" ");
    Serial.print(padValues[i]);
  }
  Serial.print("\n");
}

void printThresholds() {
+ Serial.print("t");
  for (int i = 0; i < NUM_STEPS; i++) {
    Serial.print(" ");
    Serial.print(THRESHOLDS[i]);
  }
  Serial.print("\n");
}

# config.h

  // Serial baud rate
- #define BAUD_RATE 9600
+ #define BAUD_RATE 115200

[widget-]

Oh and my editor reformatted the whole thing. If you have a preferred style I can switch to that.

[widget-]

When you await stuff you don't need to .then() it anymore. It's a little confusing but it automatically does that in the background so that you can pretend it's blocking code even though Javascript can't block.

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This parser bit is new. Incoming data goes through parser but outgoing data still goes through activePort.

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I renamed all these to make it clear that they're HTML elements.

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Since the canvas sizes are dynamic now, we can fetch them with this instead of using their default values which won't ever scale.