Added Sieve parser code in master

dev/Sieve/Extensions/rfc6609.js

@@ -0,0 +1,47 @@
+/**
+ * https://tools.ietf.org/html/rfc6609
+ */
+
+import {
+	GrammarCommand,
+	GrammarQuotedString
+} from 'Sieve/Grammar';
+
+export class IncludeCommand extends GrammarCommand
+{
+	constructor()
+	{
+		super();
+		this.global = false; // ':personal' / ':global';
+		this.once = false;
+		this.optional = false;
+		this.value = new GrammarQuotedString;
+	}
+
+	get require() { return 'include'; }
+
+	toString()
+	{
+		return this.identifier
+			+ (this.global ? ' :global' : '')
+			+ (this.once ? ' :once' : '')
+			+ (this.optional ? ' :optional' : '')
+			+ ' ' + this.value + ';';
+	}
+
+	pushArguments(args)
+	{
+		args.forEach(arg => {
+			if (':global' === arg || ':once' === arg || ':optional' === arg) {
+				this[arg.substr(1)] = true;
+			} else if (arg instanceof GrammarQuotedString) {
+				this.value = arg;
+			}
+		});
+	}
+}
+
+export class ReturnCommand extends GrammarCommand
+{
+	get require() { return 'include'; }
+}