py: Put number parsing code together in parsenum.c.
diff --git a/py/parsenum.h b/py/parsenum.h
new file mode 100644
index 0000000..5a2e42d
--- /dev/null
+++ b/py/parsenum.h
@@ -0,0 +1,2 @@
+mp_obj_t mp_parse_num_integer(const char *restrict str, uint len, int base);
+mp_obj_t mp_parse_num_decimal(const char *str, uint len);