Revert "Shell"

This reverts commit 9a2149788e.

ChangeLog

@@ -3,6 +3,8 @@
 2.3.0 () -
 
 Features
+ + #328 Replaced the 'shell' command with a standalone 'tasksh' binary, which
+   includes GNU readline support (thanks to Haitham Gad).
  + #934 support for 'reserved.lines' to accommodate multi-line
    shell prompts when used in conjunction with 'limit:page' (thanks to Robert
    Gill).

NEWS

@@ -2,6 +2,7 @@
 New Features in taskwarrior 2.3.0
 
   - New Taskserver sync capabilities.
+  - New shell (tasksh) with Readline support replaces old 'task shell' command.
   - The 'dateformat' settings now default to the ISO-8601 standard of 'Y-M-D'.
   - Italian translation.
   - French translation has begun.
@@ -15,6 +16,8 @@ New Features in taskwarrior 2.3.0
 New commands in taskwarrior 2.3.0
 
   - New 'sync' command to synchronize data with a Taskserver.
+  - New 'tasksh' command which replaces the old 'task shell' with an improved
+    standalone shell, featuring Readline support.
 
 New configuration options in taskwarrior 2.3.0
 
@@ -29,7 +32,7 @@ New configuration options in taskwarrior 2.3.0
   - The configuration file supports JSON encoding of unicode characters \uNNNN.
 
 Newly deprecated features in taskwarrior 2.3.0
-
+  
   - File format 2 (used in version 0.9.3 - 1.5.0) is no longer supported.
   - The 'push', 'pull' and 'merge' commands will be removed in version 2.4.0
     The new 'sync' command, in conjunction with the Taskserver is the new sync
@@ -43,8 +46,6 @@ Known Issues
     cause the terminal to crash when completion is invoked.  See the issue for
     full details:
     http://taskwarrior.org/issues/1352
-  - The 'tasksh' replacement for the 'shell' command is of insufficient quality,
-    and will be released later.
 
 ---