The GSN plugin is now turned off by default (it was causing too much trouble with Windows and popc). Extra search paths have been added to FindPopc for convenience. FindMeteoIO can now test if POPC is defined and tweak the searched name accordingly; but since the search result is cached with something like
	SET(POPC_EXT "popc")
	SET(METEOIO_LIBRARY "METEOIO_LIBRARY-NOTFOUND" CACHE FILEPATH "Cleared." FORCE)
	FIND_PACKAGE(MeteoIO)