Revert "demo markdown editor"

This reverts commit 732d5e6d1f5d8e21e2ef919a60cceac2b22eb8e0.

	deleted:    demo/Ui_MarkdownEditDialog.py
	deleted:    demo/mdeditdialog.ui
	deleted:    demo/myhtml2text.py
	deleted:    demo/wysdemo.py