Projects management

[aseprite-bot]

Original issue: http://code.google.com/p/aseprite/issues/detail?id=126

We should be able to manage projects. A project could:

• store settings for each sprite (?) (grid settings, palettes, brushes sizes, fg/bg colors, fav folders, etc.)
• we should be able to specify batch exports that could be done with one click/run button or triggered via CLI
• maybe a collection of extensions (?)

A possible solution would be open a folder in a tab, and that folder have a special .aseprite-project folder with possible customizations. The most important item at the moment is the possibility to create "export pipelines" (and import?), like a way to define two ways conversion between .aseprite files <-> .png files (or .gif files, etc.), this might solve issues like:

• https://community.aseprite.org/t/batch-process-for-multiple-aseprite-files/2264/2
• https://github.com/StarJackal57/Aseprite-Export-Tags/blob/master/Export%20Tags.lua
• Design a more intuitive CLI #901 (comment)
• https://community.aseprite.org/t/embed-export-settings-into-the-ase-file/17733