Update synthdefs
Add ability to specify note by string or keyword in addition to integers.

Modifiers are:

* `s` for sharp
* `b` or `f` for flat
*  [0-9] for octave

For example: 
* `note(:C)`
* `note(:C4)`
* `note(:Eb5)`
* `note("Ds")`

It's also possible to pass the octave as a second parameter:

* `note(:c, 3)`
* `note("Ds", 4)`

String/Keyword notes can now be passed to `play`:

* `play :c`
* `play "Cs5", :amp, 0.5`

Of course it's also possible to use `note` directly:

* `play note(:C3), :attack, 3`
* `play note(:c, 2)`