Amazing work so far!
It is so nice to see that open source tools are developped for cocos2d which is an open source engine.
Do you intend to keep it open source forever?
I have a feature suggestion: I saw that you already started to support multipacking as TexturePack does (i.e. creating several spritesheet in one project if one spritesheet is not enough for all imported images).
One thing that always bugged me in TexturePacker is that there is no way to group sprites in the same project so that when it is multipacking, it preferably put these sprites together. For instance, if I have a single project with many smart folders so that then can not fit on one single spritesheet, TexturePacker will dispatch sprites of the same animation on several different spritesheets while for performance reasons they should be preferably kept together on the same spritesheet, even if it means losing some space. Do you see what I mean ?
Another very important feature for me is the ability to set the anchor point position (manually or automatically for center, borders and corners), including for several sprites at the same time. Moreover, TexturePacker is especially slow when changing the anchor point fo several sprites at the same time, I think you can do better
By the way, I just briefly tested the latest release (windows 64bits), and the polygon algorithm seems to not work with multipacking.
Good luck with this project!