Refactor repository layout and convert build system to Mage.

This commit implements a massive refactor of the repository, and
moves the build system over to use Mage (magefile.org) which should
allow seamless building across multiple platforms.

tools/vendor/github.com/tmthrgd/go-bindata/stringwriter.go

@@ -0,0 +1,71 @@
+// Copyright 2017 Tom Thorogood. All rights reserved.
+// Use of this source code is governed by a Modified
+// BSD License that can be found in the LICENSE file.
+
+package bindata
+
+import "io"
+
+var (
+	stringWriterLinePrefix       = []byte(`"`)
+	stringWriterLineSuffix       = []byte("\" +\n")
+	stringWriterParensLineSuffix = []byte("\") + (\"\" +\n")
+)
+
+type stringWriter struct {
+	io.Writer
+	Indent string
+	WrapAt int
+	c, l   int
+}
+
+func (w *stringWriter) Write(p []byte) (n int, err error) {
+	buf := [4]byte{'\\', 'x', 0, 0}
+
+	for _, b := range p {
+		const lowerHex = "0123456789abcdef"
+		buf[2] = lowerHex[b/16]
+		buf[3] = lowerHex[b%16]
+
+		if _, err = w.Writer.Write(buf[:]); err != nil {
+			return
+		}
+
+		n++
+		w.c++
+
+		if w.WrapAt == 0 || w.c%w.WrapAt != 0 {
+			continue
+		}
+
+		w.l++
+
+		suffix := stringWriterLineSuffix
+		if w.l%500 == 0 {
+			// As per https://golang.org/issue/18078, the compiler has trouble
+			// compiling the concatenation of many strings, s0 + s1 + s2 + ... + sN,
+			// for large N. We insert redundant, explicit parentheses to work around
+			// that, lowering the N at any given step: (s0 + s1 + ... + s499) + (s500 +
+			// ... + s1999) + etc + (etc + ... + sN).
+			//
+			// This fix was taken from the fix applied to x/text in
+			// https://github.com/golang/text/commit/5c6cf4f9a2.
+
+			suffix = stringWriterParensLineSuffix
+		}
+
+		if _, err = w.Writer.Write(suffix); err != nil {
+			return
+		}
+
+		if _, err = io.WriteString(w.Writer, w.Indent); err != nil {
+			return
+		}
+
+		if _, err = w.Writer.Write(stringWriterLinePrefix); err != nil {
+			return
+		}
+	}
+
+	return
+}