Memcached: keep only the parser in memcached-grammar.rl.

We modify memcached code quite often,
and asking ragel to regenerate .m from .rl file
every time .rl file changed was tiresome both
for revision control and for code reviews.

Leave in memcached-grammar.rl only memcached_dispsatch(),
which is generated by ragel, and everything else
move to memcached.m. This should lessen cases
when we have to re-generate memcached-grammar.m.

This patch doesn't produce any code changes,
only moves the code (and cleans up include
files at start of memcached.m).