Include Array.prototype.map in core

[SaqImtiaz]

Firefox supports Array.prototype.map but not all browsers do. It is suggested to include it in the TiddlyWiki core, as it could be used to simplify a lot of 'for' loops in the core code, and is also very convenient for plugin writers.

Example:

var tiddlers = store.getTaggedTiddlers("task");
var titles = [];
for (var i=0; i<tiddlers.length; i++)
titles.push(tiddlers[i].title);

can be rewritten as

var tiddlers = store.getTaggedTiddlers("task");
var titles = tiddlers.map(function(t){ return t.title;});

The code in the attached path is compatible with the Firefox implementation

[JeremyRuston]

Fixed in changeset:2970