Adding tooltip support to widgets, serial connection can be restarted on the fly
Coordinator.java:
-added restartSerialConnection() (untested)

TempMonitor.java:
-code cleanup

MessageCenter.java:
-added methods to support changing serial interface on the fly

SysTray.java:
-32x32px icons

Button.java, Controller.java, Pre.java, Sensor.java, TextArea.java, ElementInterface.java:
-added support for element description (used as tooltip text)

index.css:
-small tweaks

template.html:
-switched to (semi)custom tooltip style

main.js:
-bugfixes

temp_monitor.ino:
-sketch for reading from temperature sensor