As mentioned in #26621, the block index format for era1 is not in line with the regular era block index. This change modifies the index so all relative offsets are based against the beginning of the block index record.
* all: implement era format, add history importer/export
* internal/era/e2store: refactor e2store to provide ReadAt interface
* internal/era/e2store: export HeaderSize
* internal/era: refactor era to use ReadAt interface
* internal/era: elevate anonymous func to named
* cmd/utils: don't store entire era file in-memory during import / export
* internal/era: better abstraction between era and e2store
* cmd/era: properly close era files
* cmd/era: don't let defers stack
* cmd/geth: add description for import-history
* cmd/utils: better bytes buffer
* internal/era: error if accumulator has more records than max allowed
* internal/era: better doc comment
* internal/era/e2store: rm superfluous reader, rm superfluous testcases, add fuzzer
* internal/era: avoid some repetition
* internal/era: simplify clauses
* internal/era: unexport things
* internal/era,cmd/utils,cmd/era: change to iterator interface for reading era entries
* cmd/utils: better defer handling in history test
* internal/era,cmd: add number method to era iterator to get the current block number
* internal/era/e2store: avoid double allocation during write
* internal/era,cmd/utils: fix lint issues
* internal/era: add ReaderAt func so entry value can be read lazily
Co-authored-by: lightclient <lightclient@protonmail.com>
Co-authored-by: Martin Holst Swende <martin@swende.se>
* internal/era: improve iterator interface
* internal/era: fix rlp decode of header and correctly read total difficulty
* cmd/era: fix rebase errors
* cmd/era: clearer comments
* cmd,internal: fix comment typos
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Co-authored-by: Martin Holst Swende <martin@swende.se>
