Cloudflare R2 doesn't support range options like `Range: bytes=21-`.
This patch makes FixRangeOption turn a SeekOption into an absolute
RangeOption like this `Range: bytes=21-25` to interoperate with R2.
See: #5642
Before this change FixRangeOption was leaving `Range: bytes=21-`
alone, thus not fulfilling its contract of making Range requests
absolute.
As it happens this form isn't supported by Cloudflare R2.
After this change the request is normalised to `Range: bytes=21-25`.
See: #5642
This is possible now that we no longer support go1.12 and brings
rclone into line with standard practices in the Go world.
This also removes errors.New and errors.Errorf from lib/errors and
prefers the stdlib errors package over lib/errors.
Nothing is added or removed and no package is renamed by this change.
Just rearrange definitions between source files in the fs directory.
New source files:
- types.go Filesystem types and interfaces
- features.go Features and optional interfaces
- registry.go Filesystem registry and backend options
- newfs.go NewFs and its helpers
- configmap.go Getters and Setters for ConfigMap
- pacer.go Pacer with logging and calculator
The final fs.go contains what is left.
Also rename options.go to open_options.go
to dissociate from registry options.
