"make check" / Python 1.5 compatibility fixes.

ChangeLog

@@ -13,6 +13,8 @@
 	(isalpha): New function.  Use it instead of "".isalpha.
 	(isdigit): New function.  Use it instead of "".isdigit.
 	(isupper): New function.  Use it instead of "".isupper.
+	(islower): New function.  Use it instead of "".islower.
+	(isspace): New function.  Use it instead of "".isspace.
 	(prot_a_bitstring.check_implemented): Old Python versions cannot
 	loop over a dictionary; add an explicit call to the .keys()
 	method.