Feature #158

- Added feature #158, regular expression support for filters and substitutions.
- Added unit tests to att.t and filter.t.
- Updated docs.

doc/man/task-faq.5

@@ -315,6 +315,26 @@ non-exact match:
 
 This will remove the second annotation - the first non-exact match.
 
+.TP
+.B Q: Does task support searching using regular expressions?
+Yes, taskwarrior supports IEEE Std 1003.2 (POSIX.2) regular expressions, but not
+by default.  You must enable this feature with the following command:
+
+    $ task config regex on
+
+Once enabled, all searches are considered regular expressions, for example:
+
+    $ task list ^the
+
+will list all tasks whose description or annotations start with "the".
+Substitutions also support regular expressions:
+
+    $ task 1 /^the/The/
+
+Note that regular expressions work in conjunction with the
+.B search.case.sensitive
+configuration setting.
+
 .TP
 .B Q: How can I help?
 There are lots of ways.  Here are some:

doc/man/taskrc.5

@@ -255,6 +255,18 @@ names you have used, or just the ones used in active tasks.  The default value i
 May be yes or no, and determines whether keyword lookup and substitutions on the
 description and annotations are done in a case sensitive way.  Defaults to yes.
 
+.TP
+.B regex=on
+Enables regular expression searches in filters (task list ^Fix), and
+substitutions (task <id> /^the/The/).
+
+Note that this feature works in conjunction with the
+.B search.case.sensitive
+setting.
+
+The default value is off, because this advanced feature could cause confusion
+among users that are not comfortable with regular expressions.
+
 .TP
 .B _forcecolor=no
 Taskwarrior shuts off color automatically when the output is not sent directly