patch 8.2.3562: cannot add color names

Problem:    Cannot add color names.
Solution:   Add the v:colornames dictionary. (Drew Vogel, closes #8761)
diff --git a/src/gui.c b/src/gui.c
index 1edf659..68754b3 100644
--- a/src/gui.c
+++ b/src/gui.c
@@ -4785,7 +4785,7 @@
 	    && gui.in_use
 #endif
 	    )
-	semsg(_(e_alloc_color), name);
+	semsg(_(e_cannot_allocate_color_str), name);
     return t;
 }