Move Firmata into Arduino node so we don't rely on their version of serialport

hardware/Arduino/lib/encoder7bit.js

@@ -0,0 +1,49 @@
+"use strict";
+/**
+ * "Inspired" by Encoder7Bit.h/Encoder7Bit.cpp in the
+ * Firmata source code.
+ */
+module.exports = {
+  to7BitArray(data) {
+    let shift = 0;
+    let previous = 0;
+    const output = [];
+
+    for (let byte of data) {
+      if (shift === 0) {
+        output.push(byte & 0x7f);
+        shift++;
+        previous = byte >> 7;
+      } else {
+        output.push(((byte << shift) & 0x7f) | previous);
+        if (shift === 6) {
+          output.push(byte >> 1);
+          shift = 0;
+        } else {
+          shift++;
+          previous = byte >> (8 - shift);
+        }
+      }
+    }
+
+    /* istanbul ignore else */
+    if (shift > 0) {
+      output.push(previous);
+    }
+
+    return output;
+  },
+  from7BitArray(encoded) {
+    const expectedBytes = encoded.length * 7 >> 3;
+    const decoded = [];
+
+    for (let i = 0; i < expectedBytes; i++) {
+      const j = i << 3;
+      const pos = (j / 7) >>> 0;
+      const shift = j % 7;
+      decoded[i] = (encoded[pos] >> shift) | ((encoded[pos + 1] << (7 - shift)) & 0xFF);
+    }
+
+    return decoded;
+  }
+};