Fixed costume center when importing costumes from the library or importing images into the bitmap editor
Fix choosing colors in 3D
Allow deleting procedures with recursive references
Merge pull request #256 from nathan/add-costume-offset

Fixed costume center when importing costumes from the library
Update README with recommendation to use 4.11 SDK
Clarifying update to README
Further clarifying README
Merge pull request #310 from nathan/delete-recursive-procedures

Allow deleting procedures with recursive references
Merge pull request #309 from nathan/issue/297

Fix choosing colors in 3D
Fix a typo in uiwidgets.Slider