Export: Allow using {path} similar to {name} to fetch project base directory

[Dr-Doofus]

Hi -- I've recently updated to Pixelorama v1.1.10 stable. I was poking around in the source code regarding exports and noticed that you can substitute {name} for the project name. I've tried exporting with relative filepaths such as ./{name}, but it seems to be exporting to the place Pixelorama runs from. This makes sense, and likely shouldn't be changed.

However, if one wants to export to the same folder as the project file without using the CLI, that'd be neat too. Something like {path} performing String.get_base_dir() to the location the project is stored in. In essence, this means exporting as {path}/{name} would export right next to the project file. This would enhance the workflow I'm using as I don't have to navigate using the file picker for exports.

Much appreciated! Keep up the good work!