Rename "main.py" to "__main__.py"

Now we don't need to worry about Windows compatibility, the world is a
better place.
Add Output-Format Buttons to the VisTextDisplay

Now you can output multiple things, the dialogue doesn't close after the
first result is saved, and whoop-de-doo.
Add Variable-Name Tokens in Table Output

Who calls VisTextView.trigger() gets to decide the type of object
being displayed!
Improved Table-Output Formatting

- changed it to XHTML Strict
- adjusted font-family to prefer a free typeface, so it works in the
  QtWebKit widget on my computer
Add Ctrl + w and Ctrl + q Shortcut Keys to the vis Windows
Remove Unnecessary Signals; Clean VisController Garbage

The signals and VisController were used by vis9c and prior.
Re-enable the VisOffsetSelector
Update VisOffsetSelector GUI

- add icon
- change "all" button to "none"
- set "Return" as shortcut for the checkmark/submit/whatever
- change the music21 value display from QLineEdit to QLCDNumber, since
  it's not settable and I wanted to
Overhaul VisOffsetSelector and How main.py Calls It

Now it saves lots of space! And it's efficient! Or at least less
inefficient.
Prepare for HTML-formatted Image Output (for Bar Charts, etc.)
Remove chart_view and Related Files; Switch to web_view

We'll now use the previous text_view to display both table-based output
and images.

NOTE: this commit causes breakage I'll fix in the next commits.
Rename test_display Components to web_display Components...

... and make all sorts of changes that require the next commits...
Update Image- and Table-Display XHTML Documents
Improve text_view.py to web_view.py so It's Useful

And modify views/main.py to use the new stuff. So good, so fresh!