Automatically append -DPLATFORMIO to builder

[ivankravets]

Add PLATFORMIO define to gcc builder which should be equal to platformio.__version__ in the INT format (4bytes):
1byte = major version
2byte = minor version
3byte = bug fixes number
4byte = dev/pre/post/alpha/beta and etc

Pack this information in MSB order.

[aphelps]

Hah, thanks for adding that. I had already put the same tag into all my own platformio.ini files ;)

[ivankravets]

Why you haven't requested it earlier? 😄
Do you have any ideas/propositions as for 1.1.0 release?

[aphelps]

Didn't think about it, its been a couple of weeks since I've had time to work on the software as I've needed to update the boards I've been running on it. I'll contemplate new ideas, I should be back to software development this week.

[ivankravets]

I'll contemplate new ideas, I should be back to software development this week.

Thanks! We will wait for them (ideas) 👍