patch 9.1.1051: tests: no support for env variables when running Vim in terminal

Problem:  tests: no support for env variables when running Vim in
          terminal
Solution: support the "env" argument in RunVimInTerminal(),
          close swapfiles properly in test_termcodes,
          use CheckFeature in test_termencoding

Signed-off-by: Christian Brabandt <cb@256bit.org>

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1051,
 /**/
     1050,
 /**/