'close' command should warn before closing if tiddler is dirty

[SaqImtiaz]

The tiddler toolbar's Close command should warn the user if the tiddler is dirty, similar to the Cancel command.

This protects against losing data by accidentally closing a tiddler, e.g. if the user has added the Close command to the EditTemplate? or if there are input fields in the ViewTemplate?. (Plugins and macros creating input fields in ViewTemplate? can set the dirty attribute of the tiddler when the input values are changed.)

The code cost is negligible and this is perfectly backwards compatible.

[FND]

adapted from config.commands.cancelTiddler - N.B.: uses config.commands.cancelTiddler.warning

[JeremyRuston]

Fixed in changeset:3555