Add org export-to-clipboard commands & ox-clip

These work from markdown-mode as well as org-mode. Also adds
+org/export-to-clipboard-as-rich-text for pasting org/markdown rendered
as RTF.

modules/lang/org/autoload/org-export.el

@@ -0,0 +1,49 @@
+;;; lang/org/autoload/org-export.el -*- lexical-binding: t; -*-
+;;;###if (featurep! +export)
+
+(defun +org--yank-html-buffer (buffer)
+  (with-current-buffer buffer
+    (require 'ox-clip)
+    (cond ((or IS-WINDOWS IS-MAC)
+           (shell-command-on-region
+            (point-min)
+            (point-max)
+            (cond (IS-WINDOWS ox-clip-w32-cmd)
+                  (IS-MAC     ox-clip-osx-cmd))))
+          (IS-LINUX
+           (let ((html (buffer-string)))
+             (with-temp-file "/tmp/ox-clip-md.html"
+               (insert html))
+             (apply
+              'start-process "ox-clip" "*ox-clip*"
+              (split-string ox-clip-linux-cmd " ")))))))
+
+
+;;
+;;; Commands
+
+;;;###autoload
+(defun +org/export-to-clipboard (backend)
+  "Exports the current buffer/selection to the clipboard.
+
+Prompts for what BACKEND to use. See `org-export-backends' for options."
+  (interactive
+   (list (intern (completing-read "Export to: " org-export-backends))))
+  (let ((buffer (org-export-to-buffer backend "*Formatted Copy*" nil nil t t)))
+    (unwind-protect
+        (with-current-buffer buffer
+          (kill-new (buffer-string)))
+      (kill-buffer (current-buffer)))))
+
+;;;###autoload
+(defun +org/export-to-clipboard-as-rich-text (beg end)
+  "Export the current buffer to HTML then copies it to clipboard as rich text.
+
+Supports org-mode, markdown-mode, and gfm-mode buffers. In any other mode,
+htmlize is used (takes what you see in Emacs and converts it to html, text
+properties and font-locking et all)."
+  (interactive "r")
+  (pcase major-mode
+    ((or `markdown-mode `gfm-mode)
+     (+org--yank-html-buffer (markdown)))
+    (_ (ox-clip-formatted-copy beg end))))