DCC Servo Decoder U2.3 Modular

Required libraries:
- ProjectUNION Core 0.3.0
- ProjectUNION DCC 0.3.0
- NmraDcc
- Adafruit PWM Servo Driver
- Adafruit GFX
- Adafruit SSD1306

This project must not require:
- ProjectUNION MQTT
- PubSubClient

Test:
1. Compile and note program and RAM size.
2. Confirm that no MQTT library is compiled.
3. Upload and test WiFi/web configuration.
4. Test OLED.
5. Test DCC switching.
6. Test servo A/B positions, speed and pulse limits.
7. Test OTA.
