incorrect column width for multi-byte characters by'doveadm -f table'

[Hardy Flor]

In calculating the column width multi-byte characters (eg umlauts, utf8) 
not properly analyzed:

Username mailbox        messages guid
sh_berger     Spam           0 a7b32818c14e5b54bf5500006ad9a53c
sh_berger     Entwürfe      0 a4b32818c14e5b54bf5500006ad9a53c
sh_berger     Papierkorb     0 a6b32818c14e5b54bf5500006ad9a53c