migrate fully to meson build system

- drop old build system
- move shared include and source files to common directory
- drop "rc-" prefix from shared include and source files
- move executable-specific code to individual directories under src
- adjust top-level .gitignore file for new build system

This closes #489.

man/Makefile

@@ -1,45 +0,0 @@
-MK=		../mk
-include ${MK}/sys.mk
-include ${MK}/os.mk
-
-MAN3=		einfo.3 \
-		rc_config.3 rc_deptree.3 rc_find_pids.3 rc_plugin_hook.3 \
-		rc_runlevel.3 rc_service.3 rc_stringlist.3
-MAN8=		rc-service.8 rc-status.8 rc-update.8 openrc.8 openrc-run.8 \
-		start-stop-daemon.8 supervise-daemon.8
-
-ifeq (${OS},Linux)
-MAN8 += rc-sstat.8 openrc-init.8 openrc-shutdown.8
-endif
-
-# Handy macro to create symlinks
-# This does rely on correctly formatting our manpages!
-MAKE_LINKS=	suffix=$${man\#*.}; \
-		prefix=$${man%%.*}; \
-		for link in `sed -e 's/ ,//g' \
-		-n -e '/^\.Sh NAME$$/,/\.Sh/ s/\.Nm //p' $${man}`; do \
-		if test "$${link}" != "$${prefix}" ; then \
-		ln -sf $${man} \
-		${DESTDIR}/${MANDIR}/man$${suffix}/$${link}.$${suffix} ; \
-		fi; \
-		done;
-
-include ${MK}/gitignore.mk
-
-all:
-
-install:
-	${INSTALL} -d ${DESTDIR}/${MANDIR}/man3
-	for man in ${MAN3}; do \
-		${INSTALL} -m ${MANMODE} "$$man" ${DESTDIR}/${MANDIR}/man3 || exit $$?; \
-		${MAKE_LINKS} \
-	done
-	${INSTALL} -d ${DESTDIR}/${MANDIR}/man8
-	for man in ${MAN8}; do \
-		${INSTALL} -m ${MANMODE} "$$man" ${DESTDIR}/${MANDIR}/man8 || exit $$?; \
-		${MAKE_LINKS} \
-	done
-
-check test::
-
-clean: