GPS::BBBikeGPS::MountedDevice: mount device on FreeBSD

Try to find the mount device now by looking at /var/log/messages
instead of hardcoding it to /dev/da0.
BBBikeXS: get rid of MAXPOINTS restriction
check-line-lengths: no checks for MAXPOINTS needed anymore
BBBikeXS: get rid of MAXBUF restriction
new test script for BBBikeXS' fast_plot_str() with long lines
remove now unnecessary check-line-lengths target
bbd.pod: update regarding check-line-lengths

With the latest changes in BBBikeXS.xs, the maximum buffer constraint
does not exist anymore, so remove this from the documentation.
data update (minor updates in Friedrichshain and Rummelsburg)