Replace curl completely with rclone

[marklar423]

This PR is similar to #35, but goes much further to completely remove curl as a dependency and use rclone instead.

Here's what I did:

• Removed the curl binary
• Added code to automatically download the rclone binary if it's missing
  • I wanted to just include the rclone binary in the tgz package, but it was too big (50 MiB) to fit on my device's (Kobo Libra 2) system partition (256 MiB, only 20 MiB free).
  • Instead the code uses wget to download it to .add/kobocloud/bin/ which is on the 30 GiB partition on my device.
• Changed get.sh to use wget to download NickelDBus
• Changed get.sh to use each line of the kobocloudrc file as a remote:dir pair to pass to rclone copy.
• Updated get.sh to use rclone sync instead if the REMOVE_DELETED option is present.
• Completely removed the service-specific link parsing scripts.
• Updated the README with instructions reflecting the changes.

I've built a newKoboRoot.tgz and have been using it on my device (Kobo Libra 2) to sync my Google Drive - it appears to be working well.

This is a big departure from the way things work now, but I think it brings massive improvements that make it worth it:

• Maintenance will get much easier - instead of maintaining and testing a separate script per service to manually parse and download each file, we just rely on all the work the rclone team has done to do the same thing.
• All the many, many services supported by rclone immediately become available
• Two way sync, subfolder support, and a whole lot of bugs are solved with no additional effort
  • e.g. #150 , #160 , #145 , #36
• Configuration (in my opinion) gets easier for users. While users will have to copy over the rclone.conf file, they will be able to use the interactive rclone config tool to generate the file, which will gently guide them through the process of setting up each remote service.

Please let me know your thoughts - I'm happy to discuss further and make changes.

[marklar423]

Update: I've also updated get.sh to put files for each remote in a separate subdirectory, to avoid the issue where sync (i.e. REMOVE_DELETED) removes files from other remotes, as mentioned in https://github.com/fsantini/KoboCloud/pull/35#issuecomment-738173251.

[marklar423]

For testing, I've made a release here https://github.com/marklar423/KoboCloud-rclone/releases/tag/latest

[fsantini]

Hi, thanks a lot for all your work! As this changes a lot regarding the internals of KoboCloud, I would support having it as a separate project. I am willing to give it prominence in the readme file so people can be redirected to this version, but replacing the existing workflow would disrupt too many current users, I believe (including me).

[marklar423]

Hey @fsantini thanks for taking the time to look at my PR. I totally get where you're coming from, this would definitely be a big change for existing users. So, I'll keep my fork maintained, and you can close this as obsolete or wontfix if you like.

[thocou]

Hi @marklar423 i tried your fork after resetting the factory state of my Kobo Aura 2. It works perfectly, thanks a lot to both of you ! The only issue that i have is that i see no books covers - looks like #136 Is there any way i could help you with this topic, maybe in providing logs ?