fixed extension not working consistently

update to Godot 4.4.1

fixed signed hex values in string

fixed import dialog

update to animation names

added button to create subframe outlines (applies whatever tool is assigned to left mouse)

updated animation names

fixed assembled frame and animation not updating when canvas is updated

fixed issue of assembled images not update when selected cel was changed

improved performance by moving swap_image_color to CelSelector and storing the image

fixed rotation of right-facing frames

refactored Main to use new classes

streamlined export presets

removed unsed icon

updated readme with new notes/limitations on submerged and right-facing