[lwip-members] multiple merging problem and solution

[leon . woestenberg]

This describes the problems and solution when merging from a branch
multiple times:

http://www.cvshome.org/docs/manual/cvs_5.html#SEC61

I went into this without this pre-knowledge and ran into three conflicts
which I solved too quickly. The CVS tree is now stable again, although
different compilers might issue some stuff.

Regards,

Leon Woestenberg