Enable TypeScript strict mode

[yuanqing]

• [x] Clean Document
• [x] Component Utilities
• [x] Distribute Layers
• [x] Draw Mask Under Selection
• [x] Draw Slice Over Selection
• [x] Flatten Selection to Bitmap
• [x] Format Currency
• [x] Insert Big Image
• [ ] Language Tester
• [x] Move Layers
• [x] Organize Layers
• [ ] Select Layers
• [x] Set Layer Size
• [x] Sort Layers