Started over with a fresh fork of the DMD2 library, since I'd borked
things up so badly with the old one, developing in my own branch.

After a number of Compiles and Uploads, I've found these values to be
optimal for minimal flicker.

This frees up timer1, which is used for all PWM functions on the
ESP8266/Arduino fork, as there is no hardware PWM available.

Why? Because then the DMD2 library's brightness control works.

Apart from SoftDMD, this port is now feature complete.