add explicit true/false choices for value and dest keys due to go default false for bool types

flag-types.json

@@ -3,6 +3,7 @@
     "name": "Bool",
     "type": "bool",
     "value": false,
+    "dest": true,
     "context_default": "false",
     "parser": "strconv.ParseBool(f.Value.String())"
   },
@@ -10,6 +11,7 @@
     "name": "BoolT",
     "type": "bool",
     "value": false,
+    "dest": true,
     "doctail": " that is true by default",
     "context_default": "false",
     "parser": "strconv.ParseBool(f.Value.String())"
@@ -17,6 +19,8 @@
   {
     "name": "Duration",
     "type": "time.Duration",
+    "value": true,
+    "dest": true,
     "doctail": " (see https://golang.org/pkg/time/#ParseDuration)",
     "context_default": "0",
     "parser": "time.ParseDuration(f.Value.String())"
@@ -24,12 +28,15 @@
   {
     "name": "Float64",
     "type": "float64",
+    "value": true,
+    "dest": true,
     "context_default": "0",
     "parser": "strconv.ParseFloat(f.Value.String(), 64)"
   },
   {
     "name": "Generic",
     "type": "Generic",
+    "value": true,
     "dest": false,
     "context_default": "nil",
     "context_type": "interface{}"
@@ -37,12 +44,16 @@
   {
     "name": "Int64",
     "type": "int64",
+    "value": true,
+    "dest": true,
     "context_default": "0",
     "parser": "strconv.ParseInt(f.Value.String(), 0, 64)"
   },
   {
     "name": "Int",
     "type": "int",
+    "value": true,
+    "dest": true,
     "context_default": "0",
     "parser": "strconv.ParseInt(f.Value.String(), 0, 64)",
     "parser_cast": "int(parsed)"
@@ -50,6 +61,7 @@
   {
     "name": "IntSlice",
     "type": "*IntSlice",
+    "value": true,
     "dest": false,
     "context_default": "nil",
     "context_type": "[]int",
@@ -58,6 +70,7 @@
   {
     "name": "Int64Slice",
     "type": "*Int64Slice",
+    "value": true,
     "dest": false,
     "context_default": "nil",
     "context_type": "[]int64",
@@ -66,12 +79,15 @@
   {
     "name": "String",
     "type": "string",
+    "value": true,
+    "dest": true,
     "context_default": "\"\"",
     "parser": "f.Value.String(), error(nil)"
   },
   {
     "name": "StringSlice",
     "type": "*StringSlice",
+    "value": true,
     "dest": false,
     "context_default": "nil",
     "context_type": "[]string",
@@ -80,12 +96,16 @@
   {
     "name": "Uint64",
     "type": "uint64",
+    "value": true,
+    "dest": true,
     "context_default": "0",
     "parser": "strconv.ParseUint(f.Value.String(), 0, 64)"
   },
   {
     "name": "Uint",
     "type": "uint",
+    "value": true,
+    "dest": true,
     "context_default": "0",
     "parser": "strconv.ParseUint(f.Value.String(), 0, 64)",
     "parser_cast": "uint(parsed)"