patch 8.1.1921: more functions can be used as methods

Problem:    More functions can be used as methods.
Solution:   Make various functions usable as a method.
diff --git a/src/evalfunc.c b/src/evalfunc.c
index b5e98f4..c5ec21d 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -523,41 +523,41 @@
     {"diff_hlID",	2, 2, FEARG_1,	  f_diff_hlID},
     {"empty",		1, 1, FEARG_1,	  f_empty},
     {"environ",		0, 0, 0,	  f_environ},
-    {"escape",		2, 2, 0,	  f_escape},
+    {"escape",		2, 2, FEARG_1,	  f_escape},
     {"eval",		1, 1, FEARG_1,	  f_eval},
     {"eventhandler",	0, 0, 0,	  f_eventhandler},
-    {"executable",	1, 1, 0,	  f_executable},
-    {"execute",		1, 2, 0,	  f_execute},
-    {"exepath",		1, 1, 0,	  f_exepath},
-    {"exists",		1, 1, 0,	  f_exists},
+    {"executable",	1, 1, FEARG_1,	  f_executable},
+    {"execute",		1, 2, FEARG_1,	  f_execute},
+    {"exepath",		1, 1, FEARG_1,	  f_exepath},
+    {"exists",		1, 1, FEARG_1,	  f_exists},
 #ifdef FEAT_FLOAT
     {"exp",		1, 1, FEARG_1,	  f_exp},
 #endif
-    {"expand",		1, 3, 0,	  f_expand},
-    {"expandcmd",	1, 1, 0,	  f_expandcmd},
+    {"expand",		1, 3, FEARG_1,	  f_expand},
+    {"expandcmd",	1, 1, FEARG_1,	  f_expandcmd},
     {"extend",		2, 3, FEARG_1,	  f_extend},
-    {"feedkeys",	1, 2, 0,	  f_feedkeys},
-    {"file_readable",	1, 1, 0,	  f_filereadable},	// obsolete
-    {"filereadable",	1, 1, 0,	  f_filereadable},
-    {"filewritable",	1, 1, 0,	  f_filewritable},
+    {"feedkeys",	1, 2, FEARG_1,	  f_feedkeys},
+    {"file_readable",	1, 1, FEARG_1,	  f_filereadable},	// obsolete
+    {"filereadable",	1, 1, FEARG_1,	  f_filereadable},
+    {"filewritable",	1, 1, FEARG_1,	  f_filewritable},
     {"filter",		2, 2, FEARG_1,	  f_filter},
-    {"finddir",		1, 3, 0,	  f_finddir},
-    {"findfile",	1, 3, 0,	  f_findfile},
+    {"finddir",		1, 3, FEARG_1,	  f_finddir},
+    {"findfile",	1, 3, FEARG_1,	  f_findfile},
 #ifdef FEAT_FLOAT
     {"float2nr",	1, 1, FEARG_1,	  f_float2nr},
     {"floor",		1, 1, FEARG_1,	  f_floor},
     {"fmod",		2, 2, FEARG_1,	  f_fmod},
 #endif
-    {"fnameescape",	1, 1, 0,	  f_fnameescape},
-    {"fnamemodify",	2, 2, 0,	  f_fnamemodify},
-    {"foldclosed",	1, 1, 0,	  f_foldclosed},
-    {"foldclosedend",	1, 1, 0,	  f_foldclosedend},
-    {"foldlevel",	1, 1, 0,	  f_foldlevel},
+    {"fnameescape",	1, 1, FEARG_1,	  f_fnameescape},
+    {"fnamemodify",	2, 2, FEARG_1,	  f_fnamemodify},
+    {"foldclosed",	1, 1, FEARG_1,	  f_foldclosed},
+    {"foldclosedend",	1, 1, FEARG_1,	  f_foldclosedend},
+    {"foldlevel",	1, 1, FEARG_1,	  f_foldlevel},
     {"foldtext",	0, 0, 0,	  f_foldtext},
-    {"foldtextresult",	1, 1, 0,	  f_foldtextresult},
+    {"foldtextresult",	1, 1, FEARG_1,	  f_foldtextresult},
     {"foreground",	0, 0, 0,	  f_foreground},
-    {"funcref",		1, 3, 0,	  f_funcref},
-    {"function",	1, 3, 0,	  f_function},
+    {"funcref",		1, 3, FEARG_1,	  f_funcref},
+    {"function",	1, 3, FEARG_1,	  f_function},
     {"garbagecollect",	0, 1, 0,	  f_garbagecollect},
     {"get",		2, 3, FEARG_1,	  f_get},
     {"getbufinfo",	0, 1, 0,	  f_getbufinfo},