Switch back the checksum delimiter from "!" to ":" as '!' should be escaped on non-fish shell (bash, zsh). Possible since the tx pubkeys delimiter is no longer "!"

Hi,

For issue #111 (closed) I don't get how the checksum syntax works.

There is only one call to the check_public_key() function, and it does not get the pubkey without checksum.

I tried using this feature, it does not work :

silkaj -p ts.gt.librelois.fr tx --output=J4c8CARmP9vAFNGtHRuzx14zvxojyRWHW2darguVqjtX!KAv --amount 1 --comment "BABA YAGA"
bash: !KAv: event not found

How do I get it to work ? Or should I make a MR without bothering ?a