Support pasting markdown

[jackycute]

From: hackmdio/codimd#722

@Himura2la
I used to work with HackMD as with a simple plaintext editor, I often copy-paste the markdown text to and from the hackmd window.

The recent updates brought new behavior and now I can't paste the markdown code: all my brackets and parentheses are escaped now T_T
I guess it's related to the "smart paste of HTML" feature

I found a way to import a file by drag&dropping it into the hackmd window, but when I need to add some text from another source, I have no way.

Or maybe I have?

[jackycute]

@Lin-Buo-Ren
Please allow the smart formatting conversion feature to be opted-in as it's really just making a mess in most situations.

The "paste as plaintext" feature isn't available in Mozilla Firefox for Ubuntu.

[Himura2la]

Thank you @jackycute, sorry for writing into a wrong repo

[jackycute]

@Himura2la Actually here's the repo we just created, so don't feel sorry 😃

[brlin-tw]

We should probably add a "Copy format" button in the editor toolbar and activate this feature only when the button is toggled.

[brlin-tw]

As a workaround in Firefox here's a "Copy PlainText" addon:
https://addons.mozilla.org/zh-TW/firefox/addon/copy-plaintext/

[Himura2la]

I confirm that pasting a plain text works.
It's strange that Visual Studio Code copies a formatted text...
As another workaround for those who can't use Ctrl+Shift+V, you can pass your text through any plain text editor like AkelPad on Windows or a kind of gedit/leafpad/... on Linux.

[jackycute]

Fixed by making Enable smart paste preference option of editor.