This enables the following linters
- typecheck
- unused
- staticcheck
- bidichk
- durationcheck
- exportloopref
- gosec
WIth a few exceptions.
- We use a deprecated protobuf in trezor. I didn't want to mess with that, since I cannot meaningfully test any changes there.
- The deprecated TypeMux is used in a few places still, so the warning for it is silenced for now.
- Using string type in context.WithValue is apparently wrong, one should use a custom type, to prevent collisions between different places in the hierarchy of callers. That should be fixed at some point, but may require some attention.
- The warnings for using weak random generator are squashed, since we use a lot of random without need for cryptographic guarantees.
* core/rawdb, cmd, ethdb, eth: implement freezer tail deletion
* core/rawdb: address comments from martin and sina
* core/rawdb: fixes cornercase in tail deletion
* core/rawdb: separate metadata into a standalone file
* core/rawdb: remove unused code
* core/rawdb: add random test
* core/rawdb: polish code
* core/rawdb: fsync meta file before manipulating the index
* core/rawdb: fix typo
* core/rawdb: address comments
