Support for I2C OLED Displays

[melkati]

Include full support for the most common I2C OLED Displays

• [x] Code refactor to accommodate OLED displays
• [x] Implement basic skeleton and include needed libraries and fonts
• [x] Design and convert new splash creen
• [x] Implement first display: SH1106 1.3" 128x64
• [x] Show basic data (real time CO2 measurements) on screen
• [x] Make menu work with OLED display
• [ ] Adapt setDisplayBrightness() to OLED
• [x] Test by external users
• [ ] Adapt menu to active display (p.eg: layout, font sizes, Brightness with TFT or Contrast with OLED)
• [x] Show more measurements in real time (temperature, humidity)
• [ ] Add battery icon
• [ ] Add icons for WiFi, MQTT, Bluetooth, ESP-NOW
• [x] Include flavor in Continuous Integration
• [ ] Take screenshots
• [x] Create documentation on how to use

[melkati]

Added ambient measurements to OLED display #78