Prepopulated fields in new tiddler should be readable if field is visible

[KenGirard]

If you create a newTiddler with prepopulated fields (<<newTiddler title:'New Training' tag:'workingOn' tag:'Training' template:'TrainingTemplateEdit' fields:'agreepack:"E-mail"'>> then the custom field is blank until tiddler is done. Ruins the 'prepopulated' effect.

Is there a way to get the custom field written into at creation similar to way that 'title' is?

[XavierVerges]

Story.prototype.addCustomFields() should check if the field already exists (getTiddlerField()) before creating a new invisble input field

[XavierVerges]

http://tiddlywiki.pastebin.com/f24de1652

• breaks getTiddlerField() into two methods getTiddlerFieldFromPlace()
• changes addCustomFields() to check if the field already exists before creating it