Implement a new log file format

Change from v0
- 4 byte uint path length
- 4 byte uint data length
- 8 byte uint timestamp
- path
- data
to v1:
- 1 byte record separator (0x1e)
- 2 byte uint path length
- 4 byte uint data length
- 8 byte uint timestamp
- path
- data
With this format, we can recover from a corrupted record in the file by seeking
to the next record separator.