v0.2.0 - esptool.py 1.3

esptool.py 1.3 was officially released yesterday -> upgrade it here

0.1.0 - a first milestone

• basic feature set done
• well tested on macOS, badly tested on Windows
• PyInstaller packaging done
• self-contained binary starts on Windows but fails on macOS due to pyinstaller/pyinstaller#2355

missing:

• tutorial
• input validation