Release v0.4.0

Update minimal required Go version to 1.18, and fixed some readable
atoms.

Release v0.3.1

* rmapi: Add APIResponse.Err to handle error message returned by
  reMarkable cloud API 1.5 responses.
* rmapi: Stop using empty file as default pagedata file as reMarkable
  cloud API stopped accepting any empty files for uploading.

Release v0.3.0

Breaking changes:

* rmapi: Upload no longer returns generation as it's not very useful

Other changes:

* rmapi: Add helper functions to APIResponse to for better json
  unmarshaling and preserve potential additional http headers for
  requests.
* rmapi: Handle double quoted expires json timestamp from api 1.5
  responses.
* readable: Add support to nitro-lazy-src images.
* readable: Fix a bug of handling relative image urls.
* readable&birds: Add generated meta info to final html.

Release v0.2.0

Implement reMarkable Cloud API 1.5.

Release v0.1.1

* rmapi: Set timestamp in rmapi.Upload so items are sorted correctly
  when sort by "Last updated".
* Various Readable improvements.

Release v0.1.0

First tagged release.