add .io .us .eu domain suffixes to expansion

[ctadlock]

17 bytes is not much room for a domain, forcing the use of url shorteners. By adding these other domain suffixes to the list of expansions it would allow for additional url shorteners besides the typical .com, .net....

.io
.io/
.us
.us/
.eu
.eu/

Reference: https://github.com/google/eddystone/tree/master/eddystone-url

[tsmith1985]

+1

[mkeldridge]

+1

[g-ortuno]

From @scottjenson in #154:

We've fielded this question many times. It's surprisingly hard to get agreement on what ones you should actually include. Especially as these options save just 2 bytes.

The other issue is how to roll this out. If we don't update all of the clients at the same time, we'll likely be in a situation where people will see new beacons and not be able to decode them.

There is a proposal that the PWS (which is supposed to be optional) could provide this cross over support as it could expand these new codes until the clients all update.

However, this all will likely be moot in fairly short order when BLE 5 starts to roll out. It allows Advertising packets much larger so the need for compression really goes away. Sure, it will take nearly a year to be fully deployed but it certainly feels like the right long term solution.

[ctadlock]

You misspelled "just 2 bytes", should be "12% increase".

[scottjenson]

That's totally fair. However, the other points still stand: how to handle incompatible beacons and BLE5 making this whole thing mute.

We deeply appreciate how little space this is. BLE5 can't come fast enough.