* src/lyx_main.C (init): call queryUserLyXDir just after reading

	* src/lyx_main.C (init): call queryUserLyXDir just after reading
	lyxrc.dist, but before reading lyxrc.defaults; add extra_prefix to
	the PATH before reconfiguring.
	(needsUpdate): new helper function; returns true if file does not
	exist or is older than configure.py.
	(queryUserLyXDir): check textclass.lst and packages.lst in
	addition to lyxrc.defaults.
	(reconfigureUserLyXDir): use SystemCall, since system() does not
	wait on windows.

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@13816 a592a061-630c-0410-9148-cb99ea01b6c8