Update README: VLFI is now development version of VLF.
Review fixes:
- move put statements to top level
- add write-file-functions hook locally
- vlfi-if-file-too-large becomes around advice
- minor style changes
Keep track of current batch encoded size and allow fluctuation when
searching for proper decoding.
Fix vlfi-revert to revert on user confirmation.
Update info as VLFI is merging back to VLF.  Bump version.
Use set-visited-file-name and abstract getting current file size and
updating visited time.