Add temperature, fix brightness, change how pins are toggled
Adds alphanumeric font and scrolling.
python
show('1234')
show('cool')
scroll('hello world')
scroll(list(tm1637._SEGMENTS))
Backwards compatibility issue:
If you are using `tm1637._SEGMENTS`, the `blank` and `dash` characters have been moved to the end of the font.
Previous font: `0-9`, `a-f`, `blank`, `dash`
New font: `0-9`, `a-z`, `blank`, `dash`, `star`
`blank` was segment 16 and is now segment 37.
`dash` was segment 17 and is now segment 38.