Release v4. Added features and implemented fixes follow. See README.md and manpages for documentation of new features.

• Extract user session recording functionality from tlog-rec into a new tool: tlog-rec-session. It should be used as the user's login shell now, and tlog-rec should be used as a general recording and testing tool.
• Add (optional) support for writing to and reading from Systemd Journal - the journal reader and writer.
• Make tlog-rec default to file writer, and tlog-rec-session to journal, if built with Journal support, and to syslog otherwise.
• Add -o option to tlog-rec as an alias to --file-path.
• Add -i option to tlog-play as an alias to --file-path.
• Assume locale charset is UTF-8, if ASCII charset is detected, since that is a likely indication the locale settings were lost. E.g. upon console login or su - on Fedora and RHEL.
• Switch the ver JSON field type to string. Now it should be two numbers separated by a dot. The increase of the first number indicates forward-incompatible changes, the increase of the second number - forward-compatible. If the dot and the second number are omitted, the second number is considered to be zero. Bump the format version to 2.
• Add a new JSON field: rec, containing an opaque host-unique recording ID. Bump the format version to 2.1.
• Add support for playback controls, both through the command line and via playback-time control keys, including: speed adjustment, pause/resume, fast-forward to a time, and packet-by-packet stepping through the recording.
• Add optional rate-limiting of logged messages. Both throttling and dropping messages are supported.
• Add --lax option to tlog-play to allow playing back recordings with missing messages.
• Fix input being ignored when there is a lot of output, while recording.
• Remove addition of tlog-rec (tlog-rec-session) to /etc/shells from RPM packaging to prevent users from changing their shells themselves once it has been assigned.
• Add support for specifying the shell to start via the tlog-rec-session executable name. E.g. by making a tlog-rec-session-shell-bin-zsh -> tlog-rec-session symlink and executing it. That can be used to specify particular shells to be recorded for specific users by assigning these symlinks as their login shells.
• Make error messages from all the tools a bit less noisy and more readable.