Add concept of Dictionary Tiddlers

editions/tw5.com/tiddlers/concepts/DictionaryTiddlers.tid

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+created: 20141228094500000
+modified: 20141228094500000
+tags: Concepts
+title: DictionaryTiddlers
+
+A dictionary tiddler is a [[data tiddler|DataTiddlers]] containing a simple list of name/value pairs.
+
+Its [[ContentType]] is `application/x-tiddler-dictionary`.
+
+The `text` field consists of one or more lines of the form <code>//name//: //value//</code>.
+
+[[ColourPalettes]], such as the [[default Vanilla palette|$:/palettes/Vanilla]], are dictionary tiddlers.