Add ODF compatibility function DAYS & Work around OpenOffice.org saving function names in lowercase.

2009-10-23  Andreas J. Guelzow <aguelzow@pyrshep.ca>

	* openoffice-read.c (oo_func_map_in): add EASTERSUNDAY
	  and DAYS. Use case insensitive comparison for prefixes since
	  OOo saves unknown functions in lower case.
	* openoffice-write.c (odf_func_eastersunday_handler): new
	(odf_expr_func_handler): add odf_func_eastersunday_handler and
	  DAYS translation

2009-10-23  Andreas J. Guelzow <aguelzow@pyrshep.ca>

	* functions.c (gnumeric_days): new
	(help_days): new
	* plugin.xml.in: add DAYS