patch 8.1.1610: there is no way to add or load a buffer without side effects

Problem:    There is no way to add or load a buffer without side effects.
Solution:   Add the bufadd() and bufload() functions.
diff --git a/src/version.c b/src/version.c
index 89b7f4f..6fce98b 100644
--- a/src/version.c
+++ b/src/version.c
@@ -778,6 +778,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1610,
+/**/
     1609,
 /**/
     1608,