Make linux compatible

[videgro]

Thanks for this great open source project to control the 'ITHO Eco Fan RFT' using the 'ESP8266'!

To let it compile in Arduino (1.8.5), running at Ubuntu (17.10), I made two small commits. I hope you will integrate these into the 'master'.

Bugfix: Linux is case sensitive - Include Arduino.h instead of arduino.h Bugfix: Without the typedef name, the keyword typedef is superfluous