patch 8.1.1391: no popup window support

Problem:    No popup window support.
Solution:   Add initial code for popup windows.  Add the 'wincolor' option.
diff --git a/src/evalfunc.c b/src/evalfunc.c
index 58ea710..914efb1 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -807,6 +807,10 @@
 #ifdef FEAT_PERL
     {"perleval",	1, 1, f_perleval},
 #endif
+#ifdef FEAT_TEXT_PROP
+    {"popup_close",	1, 1, f_popup_close},
+    {"popup_create",	2, 2, f_popup_create},
+#endif
 #ifdef FEAT_FLOAT
     {"pow",		2, 2, f_pow},
 #endif