doc: use the markdown format instead.
updated docs to reflect recent changes.
polished the developer build script a bit.
bugfix: made DDEBUG defineable from outside.
fixed a few debug log messages.
added more valgrind suppression rules for archlinux (gcc 4.6.0).
now we use "signed char" explicitly instead of the vague "char" type.
splitted a line exceeding 80 cols.
confirmed that we work with nginx 1.0.9.
fixed a spot that trigger the unused-but-set-variable by gcc 4.6.