Merge tag '2.4'

Version 2.4.

CHANGES

@@ -1,3 +1,83 @@
+CHANGES FROM 2.3 to 2.4 20 April 2017
+
+Incompatible Changes
+====================
+
+* Key tables have undergone major changes. Mode key tables are no longer
+  separate from the main key tables. All mode key tables have been removed,
+  together with the -t flag to bind-key and unbind-key.
+
+  The emacs-edit, vi-edit, emacs-choose and vi-choose tables have been replaced
+  by fixed key bindings in the command prompt and choose modes. The mode-keys
+  and status-keys options remain.
+
+  The emacs-copy and vi-copy tables have been replaced by the copy-mode and
+  copy-mode-vi tables. Commands are sent using the -X and -N flags to
+  send-keys. So the following:
+
+    bind -temacs-copy C-Up scroll-up
+    bind -temacs-copy -R5 WheelUpPane scroll-up
+
+  Becomes:
+
+    bind -Tcopy-mode C-Up send -X scroll-up
+    bind -Tcopy-mode WheelUpPane send -N5 -X scroll-up
+
+  This changes allows the full command parser (including command sequences) and
+  command set to be used - for example, the normal command prompt with editing
+  and history is now used for searching, jumping, and so on instead of a custom
+  one. The default C-r binding is now:
+
+    bind -Tcopy-mode C-r command-prompt -p'search up' "send -X search-backward '%%'"
+
+  There are also some new commmands available with send -X, such as
+  copy-pipe-and-cancel.
+* set-remain-on-exit has gone -- can be achieved with hooks instead.
+* Hooks: before hooks have been removed and only a selection of commands now
+  have after hooks (they are no longer automatic). Additional hooks have been
+  added.
+* The xterm-keys option now defaults to on.
+
+Normal Changes
+==============
+
+* Support for mouse double and triple clicks.
+* BCE (Background Colour Erase) is now supported.
+* All occurrences of a search string in copy mode are now highlighted;
+  additionally, the number of search results is displayed. The highlighting
+  updates interactively with the default emacs key bindings (incremental
+  search).
+* source-file now understands glob patterns.
+* Formats now have simple comparisons:
+
+    #{==:a,b}
+    #{!=:a,b}
+
+* There are the following new formats:
+
+  - #{version} -- the tmux server version;
+  - #{client_termtype} -- the terminal type of the client;
+  - #{client_name} -- the name of a client;
+  - #{client_written} -- the number of bytes written to the client.
+
+* The configuration file now accepts %if/%endif conditional blocks which are
+  processed when it is parsed; the argument is a format string (useful with the
+  new format comparison options).
+* detach-client now has -E to execute a command replacing the client instead of
+  exiting.
+* Add support for custom command aliases, this is an array option which
+  contains items of the form "alias=command". This is consulted when an
+  unknown command is parsed.
+* break-pane now has -n to specify the new window name.
+* OSC 52 support has been added for programs inside tmux to set a tmux buffer.
+* The mouse "all event" mode (1003) is now supported.
+* Palette setting is now possible (OSC 4 and 104).
+* Strikethrough support (a recent terminfo is required).
+* Grouped sessions can now be named (new -t).
+* terminal-overrides and update-environment are now array options (the previous
+  set -ag syntax should work without change).
+* There have been substantial performance improvements.
+
 CHANGES FROM 2.2 to 2.3 29 September 2016
 
 Incompatible Changes