Merge pull request #2088 from xi/titlelayout

theme: implement titleLayout

diff --cc docs/labwc-config.5.scd
Simple merge

diff --cc docs/rc.xml.all
Simple merge

diff --cc include/config/rcxml.h
Simple merge

diff --cc src/config/rcxml.c
Simple merge

diff --cc src/theme.c
Simple merge

diff --cc src/xwayland.c
Simple merge