Add ability to save/load palette

[kanurag94]

Fixes #193
Type: Enhancement

What's new?
Easy loading and sharing of palette as a .gpl extension file.
Press x to launch palette picker

[kovzol]

Thanks for this improvement!
For me, however, the usage of this window is not completely straightforward. I think:

• When selecting a .gpl file to open, the palette should be changed immediately.
• When selecting a .gpl file to save, the palette should be saved immediately.
  What do you think?

[kanurag94]

When selecting a .gpl file to open, the palette should be changed immediately.

This was my first approach, but this meant a quite number of non reusable code to be added. I agree this is not very easy to operate on.

I think there are two options:-

• Write extra code
• Provide these options as fractal->palette ->. In this we can have three options load palette file, save palette config, and palette picker instead of just palette picker. Or move these options under file.

[kovzol]

It is more intuitive to use the second option. I think it is better to keep these options in the menu where they are now (so not moving them under File).
I tried to import a .gpl file in GIMP but it was not successful. Also, when exporting a palette I got a file in .txt format like this:

#000000
#a800a8
#fc5454
...

Or am I missing something here?

[kanurag94]

I didn't check with GIMP earlier. I can reproduce this.
I'll fix this.
Thanks for reviewing :D

[kanurag94]

Also, when exporting a palette I got a file in .txt format like this:

This is basically exporting colors as hex.
Palettes are loaded in gimp app directory. To get the the actual palette, you can right click and use Show in file Manager