* eat.texi (Shell Integration): Move to be the first chapter of
Part III. Document everything about shell integration.
* eat.texi (Directory Tracking): Merge with the node 'Shell
Integration'.
* integration/bash: New file.
* eat.el (eat-term-shell-integration-directory): New variable.
Contains path to the directory containing the scripts,
automatically updated when Eat is updated.
* eat.el (eat-exec, eat-eshell-mode): New enviroment variable
'EAT_SHELL_INTEGRATION_DIR'.
* eat.texi (Shell Integration): New chapter.
* eat.texi (Directory Tracking): Refer to 'Shell Integration'.
* eat.el: Require 'url'.
* eat.el (eat-enable-directory-tracking): New user option.
* eat.el (eat--t-term): New slots: 'cwd' and 'set-cwd-fn'.
* eat.el (eat--t-set-cwd, eat-term-cwd): New function.
* eat.el (eat-term-set-cwd-function): New function and
generalized variable.
* eat.el (eat--t-handle-output): Handle OSC 7.
* eat.el (eat--set-cwd): New function.
* eat.el (eat-exec): Use 'eat--set-cwd' to change current
working directory.
* eat.el (eat--eshell-invocation-directory): New variable,
local in Eshell buffers when 'eat-eshell-mode' is enabled.
* eat.el (eat--eshell-setup-proc-and-term): Save the invocation
directory of process.
* eat.el (eat--eshell-cleanup): Revert working directory to
invocation directory.
* eat.el (eat--eshell-local-mode): When enabling, make
'eat--eshell-invocation-directory' local variable and kill when
disabling.
* eat-tests.el (eat-test-set-cwd): New test.
* eat.texi (Directory Tracking): New chapter.
