copying amount from history tab and pasting in send tab does not work

[PiRK]

The resulting amount does not have the decimal separator. We copy an XEC amount and it is somehow turned into a satoshis amount in a widget that expects XEC (so it is 100 times larger that it should be).

There seem to be two issues here:

• copy amount in the history copies the formatted string. We probably want to copy an unformatted value that can be pasted on a command line or in a spreadsheet and immediately be parsed as an amount.
• the amount widget in the send tab does a weird interpretation of the pasted string. It should probably just fail if it does not understand the value.