- Fix init_wifi: removed `ESP8266WiFiMulti`; replaced with simple
wifi ap connection
- Fix send_status: refactored return type into `bool`
- Fix send_status: optimized if-branch for calculation of `status` into
array access
- Fix send_status: removed `client.connected()` => `client.connect(...)`
is enough
- Fix: renamed `reed` into `read`
- Cleanup: changed int variables into uint8_t
- Cleanup: moved static data (`ca_certs`, `client_cert/key` into global
data
- Style: changed typedef enum into scoped enum (enum class decl)
- Style: changed int const definitions into anonymous enum constants
- Style: reorderd headers alphabetically
