patch 8.2.0847: typval related code is spread out

Problem:    Typval related code is spread out.
Solution:   Move code to new typval.c file. (Yegappan Lakshmanan, closes #6093)
diff --git a/src/globals.h b/src/globals.h
index 387c62e..89aeb96 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -1748,6 +1748,9 @@
 #ifndef FEAT_CLIPBOARD
 EXTERN char e_invalidreg[]    INIT(= N_("E850: Invalid register name"));
 #endif
+#ifdef FEAT_FLOAT
+EXTERN char e_float_as_string[] INIT(= N_("E806: using Float as a String"));
+#endif
 EXTERN char e_dirnotf[]	INIT(= N_("E919: Directory not found in '%s': \"%s\""));
 EXTERN char e_au_recursive[]	INIT(= N_("E952: Autocommand caused recursive behavior"));
 #ifdef FEAT_MENU