Renamed func_mean to func_meanw.

src/Ensstat.c

src/Fldstat.c

src/Gridboxstat.c

src/Merstat.c

src/Runstat.c

src/Seasstat.c

src/Timselstat.c

src/Timstat.c

src/Vertstat.c

src/XTimstat.c

src/Ydaystat.c

src/Ydrunstat.c

src/Yearmonstat.c

src/Yhourstat.c

src/Ymonstat.c

src/Yseasstat.c

src/Zonstat.c

src/field.c

src/field2.c

src/fieldmer.c