update urfave/cli v1.22.1, go-md2man v2.0.0, blackfriday v2.0.1

This updates urfave/cli and its dependencies to v1.22.1:

- diff for urfave/cli: https://github.com/urfave/cli/compare/v1.22.0...v1.22.1
- diff for go-md2man: https://github.com/cpuguy83/go-md2man/compare/v1.0.10...v2.0.0
- diff for blackfriday: https://github.com/russross/blackfriday/compare/v1.5.2...v2.0.1

Also adds github.com/shurcooL/sanitized_anchor_name as a new dependency, which is
used by russross/blackfriday, but will be removed again in a future update (dependency
is already removed on the v2 branch through russross/blackfriday@919b1f5b9b

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

vendor/github.com/urfave/cli/flag_bool_t.go

@@ -0,0 +1,110 @@
+package cli
+
+import (
+	"flag"
+	"fmt"
+	"strconv"
+)
+
+// BoolTFlag is a flag with type bool that is true by default
+type BoolTFlag struct {
+	Name        string
+	Usage       string
+	EnvVar      string
+	FilePath    string
+	Required    bool
+	Hidden      bool
+	Destination *bool
+}
+
+// String returns a readable representation of this value
+// (for usage defaults)
+func (f BoolTFlag) String() string {
+	return FlagStringer(f)
+}
+
+// GetName returns the name of the flag
+func (f BoolTFlag) GetName() string {
+	return f.Name
+}
+
+// IsRequired returns whether or not the flag is required
+func (f BoolTFlag) IsRequired() bool {
+	return f.Required
+}
+
+// TakesValue returns true of the flag takes a value, otherwise false
+func (f BoolTFlag) TakesValue() bool {
+	return false
+}
+
+// GetUsage returns the usage string for the flag
+func (f BoolTFlag) GetUsage() string {
+	return f.Usage
+}
+
+// GetValue returns the flags value as string representation and an empty
+// string if the flag takes no value at all.
+func (f BoolTFlag) GetValue() string {
+	return ""
+}
+
+// BoolT looks up the value of a local BoolTFlag, returns
+// false if not found
+func (c *Context) BoolT(name string) bool {
+	return lookupBoolT(name, c.flagSet)
+}
+
+// GlobalBoolT looks up the value of a global BoolTFlag, returns
+// false if not found
+func (c *Context) GlobalBoolT(name string) bool {
+	if fs := lookupGlobalFlagSet(name, c); fs != nil {
+		return lookupBoolT(name, fs)
+	}
+	return false
+}
+
+// Apply populates the flag given the flag set and environment
+// Ignores errors
+func (f BoolTFlag) Apply(set *flag.FlagSet) {
+	_ = f.ApplyWithError(set)
+}
+
+// ApplyWithError populates the flag given the flag set and environment
+func (f BoolTFlag) ApplyWithError(set *flag.FlagSet) error {
+	val := true
+
+	if envVal, ok := flagFromFileEnv(f.FilePath, f.EnvVar); ok {
+		if envVal == "" {
+			val = false
+		} else {
+			envValBool, err := strconv.ParseBool(envVal)
+			if err != nil {
+				return fmt.Errorf("could not parse %s as bool value for flag %s: %s", envVal, f.Name, err)
+			}
+			val = envValBool
+		}
+	}
+
+	eachName(f.Name, func(name string) {
+		if f.Destination != nil {
+			set.BoolVar(f.Destination, name, val, f.Usage)
+			return
+		}
+		set.Bool(name, val, f.Usage)
+	})
+
+	return nil
+}
+
+func lookupBoolT(name string, set *flag.FlagSet) bool {
+	f := set.Lookup(name)
+	if f != nil {
+		parsed, err := strconv.ParseBool(f.Value.String())
+		if err != nil {
+			return false
+		}
+		return parsed
+	}
+	return false
+}