oseamlog.sh -l [dir] improved listing format

The listing of DAT files now looks like:

DATA0072.DAT    size:  1767761  00:00:35.173 - 01:00:00.637     date: 130414  121238 - 131200  pos: 4808.705,N, 01151.461,E
DATA0073.DAT    size:  1794306  01:00:01.475 - 02:00:00.769     date: 130414  131202 - 141201  pos: 4811.265,N, 01152.158,E
DATA0074.DAT    size:  1783577  02:00:01.820 - 03:00:00.284     date: 130414  141203 - 151200  pos: 4816.561,N, 01145.086,E

This may help to get an overview which files fit together and
where and when the were recorded.
Also an optional dir name will be accepted.