Added typeface initialization to CustomLookAndFeel, and implemented
getTypefaceForFont().

Fonts can now be created using a more centralized method, by calling the
Font(String("Typeface Name"), fontHeight, Font::style) constructor.  Names for
the typefaces ("Default Light", "Paragraph") should be regarded as tentative.

There's also simpler code to do the same thing that should be uncommented after
the 2.0 update (it uses HashMap, which is not currently in our library code,
even though it's in the 1.53 docs.)

Before, EditorViewport would start accessing arrays on keypresses (specifically
the arrow keys) even when there were no editors.  This adds an extra check to
prevent this.

VS throws errors in several locations about ambigious type casting.
Fixed by removing the ambiguities and casting things to double.

The IntanThread can report TTL events on its 6 input channels. This was tested
with an Arduino; input detection is fast and reliable.

The IntanThread also generates its own timestamps, allowing the software to move
toward a framework in which timestamps come from input sources, rather than
from the RecordNode.

Finally, an ArduinoOutput module was added, which allows the software to
communicate with an Arduino via serial output.