Update v1.0.2 - Indexed Mode

This update fixes a few rare bugs and introduces a new option - Indexed Mode, when enabled, prevents new colors from being introduced, and any option that modifies colors will use colors from the palette. This was a suggestion from the Illusion of Mana.

Changes:

• [Improvement] Added an option for the Indexed Mode
• [Improvement] Colorize now works with grayscale pixels
• [Fix] Opening the Magic Pencil with an empty cel selected no longer crashes the extension
• [Fix] Adding outline to a cel with transparent pixels on the edges of the image now behaves correctly