The requirement was simply neither obvious nor intuitive. Drawback
is, the indices of temperature sensors can now differ from these
of the heaters. That's easier to recognize for newbies, though.
This is useful when operation a milling spindle. In this case,
set the spindle speed with M104 Sxxx, where xxx is 1..255.
M104 S0 turns the spindle off.
As of reprap-mendel-20100806, the RepRap java host expects resend requests using the new "rs " format only, the version before this only excepted "Resend:"
Repsnapper as of SVN 348 accepts both formats.
Also fixed typo in config.h.dist
Traumflug: to avoid breaking compatibility with earlier host versions, I took the chance to additionally introduce a sort of rudimentary version compatibility system.