dcb_remove_callback() still had the old callback prototype
fixed some warnings about const -> non-const conversions
Merge branch 'hartmut-compile-warnings' of https://github.com/hholzgra/MaxScale into hholzgra-hartmut-compile-warnings
Merge branch 'hholzgra-hartmut-compile-warnings' into release-1.0beta-refresh

Conflicts:
	server/include/dcb.h

Resolved