Write tiddlers with string fields

Otherwise date fields will get saved as JS date objects, which are not properly defined in JSON.

core/modules/tiddler.js

@@ -24,21 +24,6 @@ exports.isDraft = function() {
 	return this.hasField("draft.of");
 };
 
-exports.getFieldString = function(field,defaultValue) {
-	var value = this.fields[field];
-	// Check for a missing field
-	if(value === undefined || value === null) {
-		return defaultValue || "";
-	}
-	// Stringify the field with the associated tiddler field module (if any)
-	var fieldModule = $tw.Tiddler.fieldModules[field];
-	if(fieldModule && fieldModule.stringify) {
-		return fieldModule.stringify.call(this,value);
-	} else {
-		return value.toString();
-	}
-};
-
 /*
 Get the value of a field as a list
 */
@@ -51,24 +36,6 @@ exports.getFieldList = function(field) {
 	return $tw.utils.parseStringArray(value);
 };
 
-/*
-Get all the fields as a hashmap of strings. Options:
-	exclude: an array of field names to exclude
-*/
-exports.getFieldStrings = function(options) {
-	options = options || {};
-	var exclude = options.exclude || [];
-	var fields = {};
-	for(var field in this.fields) {
-		if($tw.utils.hop(this.fields,field)) {
-			if(exclude.indexOf(field) === -1) {
-				fields[field] = this.getFieldString(field);
-			}
-		}
-	}
-	return fields;
-};
-
 /*
 Get all the fields as a name:value block. Options:
 	exclude: an array of field names to exclude