Reorganize the folder structure for waifu'd images/pages

[bajuwa]

Currently waifu'd input images are in the same folder as the non-waifu'd images. These should instead be in their own folder. If we waifu the output images as well then we should also put those in a separate folder

Proposals:

[1]

working directory
 |---series name 
       |---input
             |---ch000
       |---input-waifud
             |---ch000
       |---compiled
             |---ch000
       |---compiled-waifud
             |---ch000

[2]

working directory
 |---series name 
       |---input
             |---ch000
             |---ch000-waifud
       |---compiled
             |---ch000
             |---ch000-prewaifud
             |---ch000-vulkan-n2-s2

[bajuwa]

In light of #104 it might be good to have the chapter folder suffixes be formed by concatenating the keyword for the 'step' to the folder name. The example folder names being something like:

• downloaded/ch000 for the raw images exactly as downloaded
• input/ch000 for input images that have potentially had ads or other images removed (manually or automatically)
• input/ch000-unmarked for input images from input/ch000 that have then had watermarks removed
• input/ch000-unmarked-prewaifud for input images from input/ch000-unmarked that have been run through waifu (prior to compilation)
• compiled/ch000-unmarked-waifud for input images from input/ch000-unmarked that have been compiled into pages before then being run through waifu