patch 7.4.918
Problem:    A digit in an option name has problems.
Solution:   Rename 'python3dll' to 'pythonthreedll'.
diff --git a/src/option.c b/src/option.c
index bc44cb2..6f9c5f5 100644
--- a/src/option.c
+++ b/src/option.c
@@ -2130,7 +2130,7 @@
 #endif
 			    {(char_u *)0L, (char_u *)0L} SCRIPTID_INIT},
 #if defined(DYNAMIC_PYTHON3) && !defined(WIN3264)
-    {"python3dll",  NULL,   P_STRING|P_VI_DEF|P_SECURE,
+    {"pythonthreedll",  NULL,   P_STRING|P_VI_DEF|P_SECURE,
 			    (char_u *)&p_py3dll, PV_NONE,
 			    {(char_u *)"", (char_u *)0L} SCRIPTID_INIT},
 #endif