Various values that we used to think of as "CONSTANT" no longer are due
to them simply not being available on a fully encrypted wallet.

This fixes the display of the various items on a change of wallet
encrytion status.

Things like 'decrypt' require us to be on the main view, so simply not
show this as it would not have any effect.

Now we provide the hamburger-menu style config option specially
for a single-wallet setup (the default when we start).
This makes available the 'encrypt' option and the 'details' option.

Newly created wallets and the default path for imported wallets now use
m/44'/0'/0'

In some cases the initially created wallet is left running and taking a
peer (in order to check if anything ever got deposited at the QR-code
shown address).
This now sunsets those wallets after 2100 blocks (over 2 weeks).

Make the re-sending of the filter happen once instead of inside the loop.

This calls the safe method instead of the 'assumed to be on the same
thread as me' method.

Add xpub getters and property + show in details

If its configurable, it should be per wallet. Not the whole app.

Also clean up the settings menu a little and provide a new QML widget:
CheckBoxLabel

Rename a pure-bitcoin-cash based method naming to no longer
have the word 'price' in it since that is associated with conversion
to another money or currency.

When the user passes in '--offline' we now prefer to show the last known
price of Bitcoin Cash.

For mined transactions we now use the historical fiat price of BCH
instead of the current.

This will give us a much more stable and historically accurate view of
our transactions.

Fixes: #7

This replaces the simple version with a proper averaging implementation
that takes all the price measurements and returns a single value per
day which is the average of all the measured ones.

When you open a pin-to-pay wallet AND within the timeout (200s) convert
it into a pin-to-open wallet AND you open it again, you might get
surprised to see it close automatically after some timeout.

Well, got to love testers to find this well hidden critter.