Update Pixi and add frame name features.

[Yukitty]

This branch updates Pixi to latest version, fixes a few bugs, and adds features to the UI for renaming added sprites / frames in the finished json.

• Double click on a frame in the sprites list to rename it
• Use frame id prepend to add a path to all
• Check the drop file ext checkbox to remove file ext (everything after and including the last . in a frame name)
• Zoom without blur
• No more canvas resize rendering bugs
• Set "trimmed: true" only on sprites that are trimmed (logic bug fix)