2011-03-28  Krzesimir Nowak  <qdlacz@gmail.com>

	Distribute doctools if non-empty parameter is passed to MM_CONFIG_DOCTOOL_DIR.

	* macros/mm-doc.m4:
	* build/doc-reference.am: If non-empty parameter is passed to
	MM_CONFIG_DOCTOOL_DIR then mm-common-prepare will copy doctools
	to given directory. These files are needed during install stage,
	so they need to be distributed. This way we don't need to add
	some lines to Makefile.am in every project using mm-common. Which
	we did, anyway.