Add ability to set custom io.writter for the Area

[linhx]

Acording to this: pterm/pterm#261 (comment)
Can I have option for setting custom io.writter for the Area.
If it is needed, can I create a PR for this?

[MarvinJWendt]

Sure, feel free to make a PR! I am currently a little busy, so it would take me a little while to get started.

[MarvinJWendt]

There is already a draft PR: #7 I don't know if it's done, or why it's still a draft. I'll wait for @Brookke to respond.