Change tabulated-list-format.

Make sure to erase the output buffer

This patch fixes the problem of not erasing the output buffer, meaning
if the buffer is re-used it will start to contain multiple outputs.

Fix read-only problematic

The dtache-log-mode enables read-only mode, so we need to disable
read-only in case the buffer is re-used.

Correct some spelling mistakes

Add default value for dtache-max-command-length

Fix bug in setup notification

Add TODO to investigate unknown inactive sessions

Update README

The readme file was incorrectly merged.

Update documentation

Update the README file as well as adding a demo.org file under
documentation.

Merge develop branch into master

This commit contains:
- An updated README.org
- A documentation folder with a demo.org file
- Functionality to determine status of a session
- Add diff session command
- Improve string representations
- Introduce dtache-env script

Merge develop branch into master

This commit contains a lot of recent improvements. To mention a few of
them:

- Dtache now has proper support for running on remote hosts
- Neither dtache.el nor dtache-shell.el have any external dependencies
- A command to list the sessions using a tabulated list interface now
if one doesn't want to use the completing-read interface
- Dtache now requires at least Emacs 27.1. This is to allow proper
customization for remote sessions
- Sessions are now launched asynchronously using start-file-process,
which takes the current default-directory into account
- Notification functionality has been implemented to notify users when
a session finishes
- dtache.el now exposes two different functions for usage of
others. The first one is dtache-shell-command, which is similar to
async-shell-command and is supposed to be used by the user
directly. The other one is dtache-start-process which targets usage
from other packages
- Sessions have been improved so that they now can store closures for
custom open/callback functionality
- The usage of the sql database has been dropped and instead reworked
to save the lisp objects to file directly for persistent storage
- Annotators have been reworked

Add missing variable to tail-mode

This commit adds the revert-buffer-preserve-modes variable and set it
to nil. The variable was missing otherwise and Emacs was complaining.

Fix dtache initialization

Fix dtache-initialize. The session directory needs to always be
checked and maybe created. The reason is that the user can have
initialized the connection to the database whilst on a remote
machine. Then on the local machine the check for initialization of the
database will be skipped, this patch makes sure that doesn't happen.

Merge develop branch into master

Merge develop branch into master

Add flycheck-mode to .dir-locals

Enable flycheck-mode to run in this project.

Add .dir-locals.el file

Merge remote branch into master

This commit adds support for running dtache in remote shells.

Add some more information to the README

Update README with links