* fixed some more bugs
* Removed some more bugs
* Added "Replace Frame" option
It was originally made to use primarily in "Spritesheet (new layer)" but it thought it could also be useful to put it there as an import option
* Update PreviewDialog.tscn
* Update PreviewDialog.gd
* Update OpenSave.gd
* added import option for SpriteSheet and Frame
Now we can add SpriteSheets in current project and Replace frames in current project
* added functions for SpriteSheet and Frames
I added functions that would allow me to add SpriteSheet as new Layer. I also added an option for "Replace frame" (the function "open_image_at_frame()" is originally being used in "open_image_as_spritesheet_layer()" method but i decided to use it as an import option as well)
* Changed contribution name
* Changed contribution name
* Fixed some lines
* fixed sprite lines not updating
This helps in previewing how each spritesheet frame will look when it will be imported in Pixelorama. Note that this does not work well with non-square images at the moment.
