As they have a pointer to each other we have to be a bit smart about how
removing works and how deletion works. Because otherwise we'll end up
with calling a deleted object.
This stops re-loading of the wallet-data on decrypt but instead keeps
the encrypted data in memory next to the (possibly) decrypted data.
This then means we can save a wallet that has its secrets still
encrypted (no password supplied) which is needed in order to propery
support the concept of xpub.
So, now a HD wallet that is closed can correctly sync and create new
public keys (which are needed to sync), including the step of saving
those to disk.
The first time the user provides a password we'll then create the
matching private keys (and their encrypted counterparts) which will then
be saved, and naturally can be used to sign transactions.
tomFlowee