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/libvterm/t/90vttest_01-movement-4.test b/src/libvterm/t/90vttest_01-movement-4.test
new file mode 100644
index 0000000..0dab3c7
--- /dev/null
+++ b/src/libvterm/t/90vttest_01-movement-4.test
@@ -0,0 +1,36 @@
+# Test of leading zeroes in ESC sequences
+INIT
+WANTSCREEN
+
+RESET
+
+PUSH "\e[00000000004;000000001HT"
+PUSH "\e[00000000004;000000002Hh"
+PUSH "\e[00000000004;000000003Hi"
+PUSH "\e[00000000004;000000004Hs"
+PUSH "\e[00000000004;000000005H "
+PUSH "\e[00000000004;000000006Hi"
+PUSH "\e[00000000004;000000007Hs"
+PUSH "\e[00000000004;000000008H "
+PUSH "\e[00000000004;000000009Ha"
+PUSH "\e[00000000004;0000000010H "
+PUSH "\e[00000000004;0000000011Hc"
+PUSH "\e[00000000004;0000000012Ho"
+PUSH "\e[00000000004;0000000013Hr"
+PUSH "\e[00000000004;0000000014Hr"
+PUSH "\e[00000000004;0000000015He"
+PUSH "\e[00000000004;0000000016Hc"
+PUSH "\e[00000000004;0000000017Ht"
+PUSH "\e[00000000004;0000000018H "
+PUSH "\e[00000000004;0000000019Hs"
+PUSH "\e[00000000004;0000000020He"
+PUSH "\e[00000000004;0000000021Hn"
+PUSH "\e[00000000004;0000000022Ht"
+PUSH "\e[00000000004;0000000023He"
+PUSH "\e[00000000004;0000000024Hn"
+PUSH "\e[00000000004;0000000025Hc"
+PUSH "\e[00000000004;0000000026He"
+
+!Output
+
+?screen_row 3 = "This is a correct sentence"