'termguicolors' #4690

TODO: Only works at startup (i.e., in the user's init.vim/vimrc/--cmd),
      but it should probably work at any time.

---

patch 7.4.1799
Problem:    'guicolors' is a confusing option name.
Solution:   Use 'termguicolors' instead. (Hirohito Higashi)
61be73bb0f

patch 7.4.1806
Problem:    'termguicolors' option missing from the options window.
Solution:   Add the entry.
8e3d1b6326

patch 7.4.1808
Problem:    Using wrong feature name to check for 'termguicolors'.
Solution:   Use the right feature name. (Ken Takata)
8a24b794b8

patch 7.4.1809
Problem:    Using wrong short option name for 'termguicolors'.
Solution:   Use the option name.
868cfc19bb

src/nvim/eval.c

@@ -10684,6 +10684,7 @@ static void f_has(typval_T *argvars, typval_T *rettv)
     "tablineat",
     "tag_binary",
     "tag_old_static",
+    "termguicolors",
     "termresponse",
     "textobjects",
     "title",