Add menu action importNoteAct to import notes from files. Currently only
HTML and Markdown files are supported. Importing other files (such as
txt) may not work correctly.
Signed-off-by: Le Tan <tamlokveer@gmail.com>
This will handle the corner case: when user open file "f" and close it,
this file is still current item, so if user want to re-open it by
clicking on it, it won't work.
Signed-off-by: Le Tan <tamlokveer@gmail.com>