An improvement to 6fb992690d
By making sure that all the popup state tiddlers have the prefix
$:/state/popup/ we can be more selective and just exclude popup state
tiddlers when we save. The end result is that once again other kinds of
state are persisted as expected (eg tabs, and sidebar visibility).
Templates are the low-level bits and pieces that allow TW5 to generate
HTML and CSS renderings of tiddlers. The UI folder contains the
user-visible UI of TW5