(bs--make-header-match-string, bs-show-in-buffer, bs--nth-wrapper): Simplify.

(bs--make-header-match-string, bs-show-in-buffer, bs--nth-wrapper): Simplify.
(bs-select, bs--insert-one-entry): Simplify.  Use `when'.
(bs-buffer-list): Simplify.  Use `when'.  Use `string-match-p'.
(bs-sort-buffer-interns-are-last): Use `string-match-p'.
(bs-attributes-list, bs-max-window-height, bs-must-always-show-regexp,
bs-maximal-buffer-name-column, bs-minimal-buffer-name-column, bs-configurations,
bs-default-configuration, bs-alternative-configuration,
bs-cycle-configuration-name, bs-string-show-always, bs-string-show-never,
bs-string-current, bs-string-current-marked, bs-string-marked,
bs-string-show-normally, bs-sort-functions, bs-default-sort-name):
Remove * in docstrings.
(bs--redisplay, bs--goto-current-buffer, bs--current-buffer, bs-delete,
bs-apply-sort-faces, bs-next-config-aux): Use `when'.
(bs--window-config-coming-from): Revert 2006-11-09 change.
(bs--restore-window-config): Keep the selected frame.
(bs--track-window-changes, bs--remove-hooks): New functions.
(bs-mode): Use `define-derived-mode'.  Set hook to track window changes.
(bs--create-header): Remove.
(bs--create-header-line): New function, based on `bs--create-header'.
(bs--show-header): Use `bs--create-header-line'.
(bs--show-with-configuration): Revert 2006-11-09 change.
Don't reuse window unless it is visible on the selected frame.
Restore window configuration (possibly in a different frame)
before creating any window.