Fix for issue (#70) with Greenland DST rule.
Thanks to @mabartibin for catching this.

Tested on Raspberry Pi Pico.
Change library.properties to have architecture=*.

Add depends to library.properties.

Fix buffer overrun in example sketches.

Add example sketch to test library operation.

Constructors needed to initialize the variables that contain the DST and standard time start points for local time and UTC. If Timezone objects were dynamically allocated (with new), then deleted and re-allocated, residue in the uninitialized variables could cause functions (e.g. utcIsDST()) to return invalid results. This would also theoretically be possible when not using dynamic allocation, but would be exceedingly rare.

• Add constructor for time zones that do not observe daylight time.
• Update example sketch.

Update example sketches:

• Fix compiler warnings,
• Button library name change,
• Shorter code for function to print date and time.