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/GoASTScanner/gas/config.go

@@ -0,0 +1,88 @@
+package gas
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"io/ioutil"
+)
+
+const (
+	// Globals are applicable to all rules and used for general
+	// configuration settings for gas.
+	Globals = "global"
+)
+
+// Config is used to provide configuration and customization to each of the rules.
+type Config map[string]interface{}
+
+// NewConfig initializes a new configuration instance. The configuration data then
+// needs to be loaded via c.ReadFrom(strings.NewReader("config data"))
+// or from a *os.File.
+func NewConfig() Config {
+	cfg := make(Config)
+	cfg[Globals] = make(map[string]string)
+	return cfg
+}
+
+// ReadFrom implements the io.ReaderFrom interface. This
+// should be used with io.Reader to load configuration from
+//file or from string etc.
+func (c Config) ReadFrom(r io.Reader) (int64, error) {
+	data, err := ioutil.ReadAll(r)
+	if err != nil {
+		return int64(len(data)), err
+	}
+	if err = json.Unmarshal(data, &c); err != nil {
+		return int64(len(data)), err
+	}
+	return int64(len(data)), nil
+}
+
+// WriteTo implements the io.WriteTo interface. This should
+// be used to save or print out the configuration information.
+func (c Config) WriteTo(w io.Writer) (int64, error) {
+	data, err := json.Marshal(c)
+	if err != nil {
+		return int64(len(data)), err
+	}
+	return io.Copy(w, bytes.NewReader(data))
+}
+
+// Get returns the configuration section for the supplied key
+func (c Config) Get(section string) (interface{}, error) {
+	settings, found := c[section]
+	if !found {
+		return nil, fmt.Errorf("Section %s not in configuration", section)
+	}
+	return settings, nil
+}
+
+// Set section in the configuration to specified value
+func (c Config) Set(section string, value interface{}) {
+	c[section] = value
+}
+
+// GetGlobal returns value associated with global configuration option
+func (c Config) GetGlobal(option string) (string, error) {
+	if globals, ok := c[Globals]; ok {
+		if settings, ok := globals.(map[string]string); ok {
+			if value, ok := settings[option]; ok {
+				return value, nil
+			}
+			return "", fmt.Errorf("global setting for %s not found", option)
+		}
+	}
+	return "", fmt.Errorf("no global config options found")
+
+}
+
+// SetGlobal associates a value with a global configuration ooption
+func (c Config) SetGlobal(option, value string) {
+	if globals, ok := c[Globals]; ok {
+		if settings, ok := globals.(map[string]string); ok {
+			settings[option] = value
+		}
+	}
+}