v0.15 is here

Hy, so i know i made an update just yesterday but i found some more bugs to fix so here's another update

• Fixed data not updating if we assign pose layer through menu button.
• Fix bone ghosting issue on frames not in focus when a group was removed or added.
• Added ability to add Pixel Layers through bone properties.
• Fixed some UI signals not reconnecting if a group layer has no textures.
• Fixed Groups with same name appearing and causing conflict when using add layer button.