This option allows combine big file when disk space is low.
it's not enabled by default to allow easy redownload/retry.

- switched to tinylog, it supports log level
- reorganize files to minimize code recompilation
- added --verbose for rd-api
- make FileStatus a data type
- update doc

For port number, if parse fail, it will exit on start up.
previously env var with parse error are ignored silently.

- should use strOption for string parameters.
- also fix rd-api Main, should use cli args parsed result as base config
  in runtimeConfig.
- rd-api now support env variables for all params.

it will act like a static file server

after decimal point

- moved version string to CliVersion module
- update pypi Makefile to check README.rst syntax before creating wheel

tinylog is based on fast-logger and supports log levels.
I need log level support in rd client, for the --verbose option.

- use fast-logger to do logging
- use ExceptT to do early return
- extract getRdHandler and DB functions, code is more clean now

code removed from this repo.

dropped async, used self implemented Task.

add help doc for rd-api

- update "debug opts" to use putStrLn. no stupid quotes around string.
- add retry support for fetchBlockFromHttp (--block-max-retry)
- check http status code
  expect 200 on GET /rd/file.
  expect 206 on GET /file with Range header.
- handle http exceptions
- handle IOError at critical places.
- on client tool, use MaybeT to do early return, avoid shifting to the right.
- fix -f -v wrong option position in parser.
- other small fixes.

- enable -Wall -Werror in package.yaml
  fix issues
- support "pending" blocks. client will do incrementally download until
  all blocks are ready on server side and fetched to local disk.
- bugfix: fileWorker missing "forever" loop.
- moved genBlocks to RD.Lib

bugfix: worker should close file when done

sha1sum works fine with lazy ByteString.