Add vterm layer

vterm layer uses emacs-libvterm for terminal support

modules/emacs/vterm/config.el

@@ -0,0 +1,27 @@
+;;; emacs/vterm/config.el -*- lexical-binding: t; -*-
+
+(def-package! vterm
+  :load-path (lambda () (list (concat doom-packages-dir "/quelpa/build/vterm")))
+  :init
+  (unless (file-executable-p (concat
+                              (file-name-directory (locate-library "vterm"))
+                              "vterm-module.so"))
+    ;; let vterm compile `vterm-modules.so'
+    (setq-default vterm-install t))
+  :when (and (string-match-p "MODULES" system-configuration-features)
+             (display-graphic-p))
+  :config
+  (set-env! "SHELL")
+  (add-hook 'vterm-mode-hook #'doom|mark-buffer-as-real)
+  ;; Automatically kill buffer when vterm exits.
+  (setq-default vterm-exit-functions #'kill-buffer)
+  (when (featurep! :feature evil)
+    (evil-set-initial-state 'vterm-mode 'insert)
+    ;; Those keys are commonly needed by terminals.
+    (evil-define-key 'insert vterm-mode-map
+      (kbd "C-d") #'vterm--self-insert)
+    ;; Go back to normal state but don't move cursor backwards.
+    ;; Moving cursor backwards is the default Vim behavior but
+    ;; it is not appropriate in some cases like terminals.
+    (add-hook 'vterm-mode-hook #'(lambda ()
+                                   (setq-local evil-move-cursor-back nil)))))