Paste from the changelog:
There have been a lot of changes. Here are the highlights:
* Improved command line parser: terminator -- handling, UUID
recognition, DOM recognition, red-herring pairs (foo:bar), escaped
slashes in patterns (/one\/two/), substitutions (/one\/two/one-two/),
Unicode U+NNNN and \uNNNN, escaped entities (\n, \t etc) for use in
descriptions/annotations, abbreviated day and month names, ISO-8601
durations (PT4H, P1Y etc).
* New virtual tags UDA, ORPHAN, PROJECT, PRIORITY, and LATEST.
* Improved support for DOM references in filters task
'due.year = 2015 and due.week > 20' list.
* New configuration settings urgency.inherit, rule.color.merge,
urgency.user.tag.next.coefficient, color.uda.<name>.none, sugar,
report.<name>.sort:none, json.depends.array.
* Improved urgency: the urgency.inherit setting propagates urgency
along dependency chains.
* Improved searching: more powerful regular expressions.
* Improved attribute modifiers: is/isnt are now consistent exact
match operator equivalents to ==/!==.
* New command _unique, for generating unique lists of values, and
will ultimately replace several helper commands.
* New command commands, which lists commands and details about how
they affect filters, GC, context, and syntax.
* New verbosity tokens recur (feedback when a recurring task instance
is created), unwait (for when a waiting task becomes visible).
* Improved extensions: zsh completion, Fish shell completion, add-on
scripts now online.
* Improved documentation: help command, man pages, more online docs,
negation ! operator, sample hook scripts.
* Improved sync: GnuTLS now mandatory, so everyone has the sync
command.
* Improved JSON import/export support: free-format JSON, task arrays
assumed (which makes import/export work with out-of-the-box parsers),
dependencies optionally modeled as an array, UUIDs validated, tasks
added/updated without duplication, import from STDIN using -.
* Improved performance: less data is read from disk depending on the
filter.
* Improved diagnostics: duplicate dependency warnings, multi-task
edit failures, changes to tasks without IDs, certificate file sizes.
* Improved testing: migrated all Perl tests to Python, parallelized
test suite, colorized output, detection of newly passing tests,
Python 2.7 and 3 support, better debug output, Bash test library,
stress test tool, no more disabled tests - everything runs, test
coverage is now 87.3%.
* Widespread code cleanup, removal of dead code, C++11 enhancements,
improved portability, merged ISO-8601 and legacy durations, less
code, happier developers.
