Need a method to set the index lookahead for Wallet

[danielabrozzoni]

See #1152 (comment)

[nondiremanuel]

@notmandatory why in alpha.4? I see it will be closed by #1172 that is in the alpha.3

[notmandatory]

I think I moved it based on the title without seeing the comment that it's linked to #1172.

[notmandatory]

Should be fixed by #1229