Added first version of extrude

Note this will work only with 1 pixel extrusion.
rect.width to rect.height
- Now AtlasBuilder is a instance class, no static.
- Added constructor parameters maxWidth and maxHeight
- Split build into 2 methods: buildBitmapData and buildTextureAtlas
- Added powerOfTwo, square and imagePath parameters in build Methods.
- Add reset and dispose methods
- Add appendBitmap method. You can use to build one by one the atlas to know if the bitmap is inserted.
- Improvement: If extrude = 0, this step is skipped.
- Improvement: If the bitmap can't be inserted, then it will avoid the extrusion.
- Fix: !rect check in wrong place.
- It will have always the minimum texture size.
- Added static method createMultipleAtlas. It will create multiple textures with single bitmap list if the limit is reached.