Fix --section-start handling and add --map to ld wrapper. Fixed error where --section-start was passed to lwlink instead of --section-base. Also added --map to ld wrapper. Thanks to pulkomandy@pulkomandy.tk for pointing out the former and mentioning the lack of the latter.

The lwbasic directory is an in-progress attempt to write a compiler for a
dialect of basic specifically targetted at the 6809 CPU. It is still
incomplete but is included in this distribution in case someone finds the
code useful. It is not built by default.