patch 8.2.2339: cannot get the type of a value as a string

Problem:    Cannot get the type of a value as a string.
Solution:   Add typename().
diff --git a/src/evalfunc.c b/src/evalfunc.c
index 65cb59f..0e6d759 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -1742,6 +1742,8 @@
 			ret_float,	    FLOAT_FUNC(f_trunc)},
     {"type",		1, 1, FEARG_1,	    NULL,
 			ret_number,	    f_type},
+    {"typename",	1, 1, FEARG_1,	    NULL,
+			ret_string,	    f_typename},
     {"undofile",	1, 1, FEARG_1,	    NULL,
 			ret_string,	    f_undofile},
     {"undotree",	0, 0, 0,	    NULL,