ESP8266 fix

[sej7278]

Fixes issue #10

[mfaheemakhtar]

@sej7278, I saw that your fix has not been merged yet. I've embed your fix in my forked version. :)

https://github.com/mfaheemakhtar/LedControl-F

Hope you will not mind. :D

[microwiz]

This needs to be merged.

[bertrik]

Using platformio, you can test that it works using:
pio ci examples/LCDemoMatrix --lib=. --board=d1_mini
and for the atmel avr arduinos:
pio ci examples/LCDemoMatrix --lib=. --board=uno