patch 8.0.0693: no terminal emulator support

Problem:    No terminal emulator support.  Cannot properly run commands in the
            GUI.  Cannot run a job interactively with an ssh connection.
Solution:   Very early implementation of the :terminal command.  Includes
            libvterm converted to ANSI C.  Many parts still missing.
diff --git a/src/ex_cmdidxs.h b/src/ex_cmdidxs.h
index 3b6120e..4d3bcbe 100644
--- a/src/ex_cmdidxs.h
+++ b/src/ex_cmdidxs.h
@@ -25,12 +25,12 @@
   /* r */ 351,
   /* s */ 370,
   /* t */ 437,
-  /* u */ 472,
-  /* v */ 483,
-  /* w */ 501,
-  /* x */ 516,
-  /* y */ 525,
-  /* z */ 526
+  /* u */ 473,
+  /* v */ 484,
+  /* w */ 502,
+  /* x */ 517,
+  /* y */ 526,
+  /* z */ 527
 };
 
 /*
@@ -60,7 +60,7 @@
   /* q */ {  2,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0 },
   /* r */ {  0,  0,  0,  0,  0,  0,  0,  0, 11,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0, 13, 18,  0,  0,  0,  0 },
   /* s */ {  2,  6, 15,  0, 18, 22,  0, 24, 25,  0,  0, 28, 30, 34, 38, 40,  0, 48,  0, 49,  0, 61, 62,  0, 63,  0 },
-  /* t */ {  2,  0, 19,  0, 22, 23,  0, 24,  0, 25,  0, 26, 27, 28, 29, 30,  0, 31, 33,  0, 34,  0,  0,  0,  0,  0 },
+  /* t */ {  2,  0, 19,  0, 22, 24,  0, 25,  0, 26,  0, 27, 28, 29, 30, 31,  0, 32, 34,  0, 35,  0,  0,  0,  0,  0 },
   /* u */ {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0, 10,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0 },
   /* v */ {  0,  0,  0,  0,  1,  0,  0,  0,  4,  0,  0,  0,  9, 12,  0,  0,  0,  0, 15,  0, 16,  0,  0,  0,  0,  0 },
   /* w */ {  2,  0,  0,  0,  0,  0,  0,  3,  4,  0,  0,  0,  0,  8,  0,  9, 10,  0, 12,  0, 13, 14,  0,  0,  0,  0 },
@@ -69,4 +69,4 @@
   /* z */ {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0 }
 };
 
-static const int command_count = 539;
+static const int command_count = 540;