Fixed broadcasts created in palette not being accessible via menu
Fixed duplication when dragging media into the backpack
Fixed incorrect caching in primVarSet and primVarChange
Fixed shadow disappearing when a script runs while being dragged
Fixed dragging "when Stage clicked" into a sprite
Fixed not being able to drop block when color picker was under mouse
Fixed rounding costume center coordinates in vector mode

This also doubles the resolution of the bitmap costume center tool so that it lines up with the actual pixels of the image.
Allow wrapping C blocks in the middle of a stack
Made attribute block update when switching sprite

If the sprite you switch to doesn’t have an attribute or variable, it
will set the attribute to the default one for sprites or the stage.
Shortened the code a little
Changed "allowed" to "valid"

I think it makes a little more sense.
Use translated default values
Revert "Use translated default values"

This reverts commit 0c7de21dc3b1092d055b9bf294280a64431f856b.
Use GestureHandler as source for bubbles it creates

Shane explained that it would make more sense to use the GestureHandler
as the source for these particular TalkBubble instances.
Fixed costume center button being too far to the right
Merge pull request #243 from nathan/wrap-c-in-stack

Allow wrapping C blocks in the middle of a stack
Added Letters category to media library
Merge pull request #254 from nathan/letters-category

Added "Letters" category to media library
Fixed setting slider min/max not triggering autosave
Fixed pressing keys while drawing with the pencil