Initial Commit

Carried over from the abortive pull request #169
Fixes to make SVG and MathML elements work properly
Add button widget
Refactor macro parameter substitution

Now macros can also include references to variables as `$(variable)$`
Add support for macro definitions
Add a class for missing tiddlers
More useful class variables for tiddler status
Fixes to get recent changes list to work
Use the setvariable widget instead of macrodef

setvariable is more general
Deal with viewing date fields that don't exist
Make recursion markers include the current tiddler

Otherwise the generated qualifying state title is not unique. In other
words, clicking the "i" button on a tiddler was opening the info panels
for all open tiddlers.
Proper styling for the tiddler info panel
Correct name for the state tiddler that makes sure the open sidebar tab is open by default
Fixes to button refreshing
A new template for menu list items
Support selectedClass properly in the button widget
Style for selected tiddler info button
Fixups to the sidebar and tiddler info button
Get the tiddler info panel fields list working properly

Now we can display the fields list as a proper table.

We've had to temporarily hack the list widget again…
Add macrocall widget

Now the fields table works in the tiddler info popup