Fix the execution context for widget attributes specified as macros

We need to ensure that variables in the tree up to this point are
accessible when we render the macro text.
Correct typo
For tw5.com add a link in the info panel to the static tiddler representation
Add urlencoded and doubleurlencoded formats to the view widget
Fix typo
Fix up prematutely committed static link tab for tw5.com
First pass at a saver for IE10 and above

It's not great, sadly. Clicking save in the browser pulls up an
unobtrusive bar at the bottom of the browser window where you can click
"save". You then get a new copy of your wiki in the downloads folder.
Docs update
Removed inadvertent alert()
Fix $tw.utils.hasClass() to work even if the element doesn't have a className property
Improve popup dismissal

Now we ignore clicks if they come from an element that has an ancestor
with the class `tw-popup`
Update the reveal widget to set the tw-popup class
Update the tiddler info panel to use the new tw-popup class

This fixes the problem with the inability to click on items within the
tiddler info panel (including the static URL)
Fix view format=date so that it doesn't crash on empty fields
Docs update
Use prototypal inheritance to speed up the inheritance of widget variables

Now we reuse the prototype mechanism to let javascript do the work of
searching up the parent chain.
Tweaks tests

This was the only place we were using the `variables` option to the
widget constructor.
Improve performance of tag handling with some caching
Better styling for embedded PDFs
Rename the 'setvariable' widget to 'set'

Sleeker.