Show alert if no input on #password page
Do not fail with empty password when on #layout
Fix password selector

* revise first-time-use screen
* generate password (policy applies)
* hide/reveal password text for sta/admin settings
* changed autocomplete='...' for some inputs to avoid completion

* fix webui regexp and input length limits
* explain requirements in webui and headers

* Works with many different ultrasonic sensor models: HC-SR04, SRF05,
  SRF06, DYP-ME007, JSN-SR04T & Parallax PING)))™.
* Built-in digital filter method ping_median() for easy error correction
  (use SONAR_ITERATIONS build flag to configure).
* Allows setting of a maximum distance where pings beyond that distance
  are read as no ping or clear (use SONAR_MAX_DISTANCE build flag).

improved CSS to comply with CODACY rules

also minor html fixes

- Integrated Geiger Counter
- Adapted sensor.ino to read and publish values.
- Modified html to add local dose rate into web page.
- Tested with influxDB.
- Tested with MQTT.