patch 8.1.1785: map functionality mixed with character input

Problem:    Map functionality mixed with character input.
Solution:   Move the map functionality to a separate file. (Yegappan
            Lakshmanan, closes #4740)  Graduate the +localmap feature.
diff --git a/src/proto.h b/src/proto.h
index 2257012..34ef9cc 100644
--- a/src/proto.h
+++ b/src/proto.h
@@ -98,6 +98,7 @@
 # include "list.pro"
 # include "blob.pro"
 # include "main.pro"
+# include "map.pro"
 # include "mark.pro"
 # include "memfile.pro"
 # include "memline.pro"