patch 8.1.0363: internal diff isn't used by default as advertised

Problem:    Internal diff isn't used by default as advertised.
Solution:   Add "internal" to the default value of 'diffopt'.
            Also add couple of files missing from the distribution.
diff --git a/src/option.c b/src/option.c
index 98ef98a..f47549d 100644
--- a/src/option.c
+++ b/src/option.c
@@ -1049,7 +1049,7 @@
 								     |P_NODUP,
 #ifdef FEAT_DIFF
 			    (char_u *)&p_dip, PV_NONE,
-			    {(char_u *)"filler", (char_u *)NULL}
+			    {(char_u *)"internal,filler", (char_u *)NULL}
 #else
 			    (char_u *)NULL, PV_NONE,
 			    {(char_u *)"", (char_u *)NULL}
diff --git a/src/version.c b/src/version.c
index 13c61b8..853c86f 100644
--- a/src/version.c
+++ b/src/version.c
@@ -795,6 +795,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    363,
+/**/
     362,
 /**/
     361,