enhanced moo_inttostr() with 2 new flags - MOO_INTTOSTR_LOWERCASE and MOO_INTTOSTR_NONEWOBJ

redefined bigint and fpdec check macros
added the strfmt primitive to String

moo/kernel/Collect.moo

@@ -265,6 +265,8 @@ class(#character) String(Array)
 	 * if no terminating null character exists, it returns the same value as the size method *)
 	method(#primitive,#lenient) _strlen.
 	method(#primitive) strlen.
+
+	method(#primitive,#variadic) strfmt().
 }
 
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