facilitate creating pages

[edrex]

I often create a page per task, for notes/references etc. It would be nice if I could create/jump to the page from the task line and also interact with the task from the task page (same bindings as when cursor is on a task line)

• Forward link could be as https://github.com/ValiValpas/taskopen (full filesystem path or with ~)
• Back link could be represented in the page text somehow, maybe as a task line with a special heading.

A lot of UI decisions to make, but the basic functionality seems very useful.

[nkakouros]

Duplicate of #217.

[nkakouros]

@edrex @tbabej This can be closed as duplicate.