Release 0.91

• Allows to set a http callback for button presses via dev.json.
• You can send a 8x8 jpg icon as base64 string.
• Applies gamma correction to brightness control
• IP adress was added to stats
• MQTT client uses uniqueID
• Uptime reading now handles the millis() overflow to calculate longer uptime than 49days
• Fixes a bug where duration wasnt reset after custom app deletion. closes #407
• Indicator fading and blinking options are now disabled after deactivation. closes #402
• Awtrix sends the stats only after the first full sensor reading to avoid zero numbers after boot. closes #391
• Fixes some minor bugs