patch 8.1.0588: cannot define a sign with space in the text

Problem:    Cannot define a sign with space in the text.
Solution:   Allow for escaping characters. (Ben Jackson, closes #2967)
diff --git a/src/version.c b/src/version.c
index cc60996..3c9eb0d 100644
--- a/src/version.c
+++ b/src/version.c
@@ -800,6 +800,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    588,
+/**/
     587,
 /**/
     586,