Add an option to change amount-alignment mode.
Add an option to change amount-alignment mode.

Make the default alignment behaviour the same as before 767ab3e, that
is, align on the last digit by default.  A new option
`ledger-post-amount-alignment-at' now exists to adjust alignment
preference.

afh/ledger,afh/ledger,ledger/ledger,afh/ledger,afh/ledger,ledger/ledger,ledger/ledger,afh/ledger,ledger/ledger,ledger/ledger