feature request: config to add/change current project

**Background:** Most (not all) of my work has a consistent project for a number of issues at a time, so having to retype it over and over, then add the issue id number can be irritating (especially if the current project has a long ID).

**Request:** I'm thinking it would be good to have a config option that lets you set the project prefix so all you have to do is type the number of the issue - until you change it. Or if you are working in between projects all day you just leave the config value empty and it asks you to complete the whole thing.

I'll just leave this request here in case someone (or I) can get some work done on this and do a PR.

Thanks!