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/alecthomas/gometalinter/config.go

@@ -2,6 +2,8 @@ package main
 
 import (
 	"encoding/json"
+	"os"
+	"path/filepath"
 	"runtime"
 	"text/template"
 	"time"
@@ -38,6 +40,7 @@ type Config struct { // nolint: maligned
 	Vendor          bool
 	Cyclo           int
 	LineLength      int
+	MisspellLocale  string
 	MinConfidence   float64
 	MinOccurrences  int
 	MinConstLength  int
@@ -128,6 +131,7 @@ var config = &Config{
 	Concurrency:     runtime.NumCPU(),
 	Cyclo:           10,
 	LineLength:      80,
+	MisspellLocale:  "",
 	MinConfidence:   0.8,
 	MinOccurrences:  3,
 	MinConstLength:  3,
@@ -135,3 +139,54 @@ var config = &Config{
 	Sort:            []string{"none"},
 	Deadline:        jsonDuration(time.Second * 30),
 }
+
+func loadConfigFile(filename string) error {
+	r, err := os.Open(filename)
+	if err != nil {
+		return err
+	}
+	defer r.Close() // nolint: errcheck
+	err = json.NewDecoder(r).Decode(config)
+	if err != nil {
+		return err
+	}
+	for _, disable := range config.Disable {
+		for i, enable := range config.Enable {
+			if enable == disable {
+				config.Enable = append(config.Enable[:i], config.Enable[i+1:]...)
+				break
+			}
+		}
+	}
+	return err
+}
+
+func findDefaultConfigFile() (fullPath string, found bool, err error) {
+	prevPath := ""
+	dirPath, err := os.Getwd()
+	if err != nil {
+		return "", false, err
+	}
+
+	for dirPath != prevPath {
+		fullPath, found, err = findConfigFileInDir(dirPath)
+		if err != nil || found {
+			return fullPath, found, err
+		}
+		prevPath, dirPath = dirPath, filepath.Dir(dirPath)
+	}
+
+	return "", false, nil
+}
+
+func findConfigFileInDir(dirPath string) (fullPath string, found bool, err error) {
+	fullPath = filepath.Join(dirPath, defaultConfigPath)
+	if _, err := os.Stat(fullPath); err != nil {
+		if os.IsNotExist(err) {
+			return "", false, nil
+		}
+		return "", false, err
+	}
+
+	return fullPath, true, nil
+}