[Feature] Add advanced editor for Paste

[guidoeffe]

Hi,
I think that Paste is very useful to store pieces of code in private mode (self-hosted) and I use it to edit or re-edit functions before pasting them to the original file.
I think that should be a very interesting feature to have Ace editor (https://ace.c9.io/) or some like it that help coding correctly.
Thanks for all.