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/README b/src/libvterm/README
new file mode 100644
index 0000000..ef74b01
--- /dev/null
+++ b/src/libvterm/README
@@ -0,0 +1,13 @@
+This is a MODIFIED version of libvterm.
+
+The original can be found:
+On the original site (tar archive and Bazaar repository):
+	http://www.leonerd.org.uk/code/libvterm/
+Cloned on Github:
+	https://github.com/neovim/libvterm
+
+Modifications:
+- Add a .gitignore file.
+- Convert from C99 to C90.
+- Other changes to support embedding in Vim.
+-