timeline

The 1.6 series sees a continued refactoring, to reduce dependencies between modules and facilitate unit-testing

The 1.5 series of webtrees raises the minimum PHP version from 5.2 to 5.3.
The aim of this series is for internal refactoring to improve performance and prepare for the final switch to an MVC framework

The 1.4 series refactored lots of internal media handling.
The media firewall was simplified, and integrated into the core code.

Many performance tweaks - our PageSpeed and YSlow scores are close to 100%.

The 1.3 series includes lots of internal refactoring.

Many of these affect performance - our PageSpeed and YSlow scores are well over 90%
The themes make better use of sprites
Replace many popup windows with modal dialog boxes
Pending changes are used in many more places, including charts
A new "error checker" has been introduced to replace the old gedcheck.php script.
Default settings for new trees and users

The 1.2 series includes:

A rewrite of the privacy functions to achieve a significant performance boost.
A rewrite of some media library functions, to achieve a significant performance boost, and prepare for simplification/integration of the media firewall function.
A redesigned header for the individual page
Much greater use of CSS for styling, including sprite-based CSS menus on some of the themes (the others to follow)

...plus many other minor improvements

The webtrees 1.1 series introduces many changes to 1.0.

The module/theme interface is changed (and incompatible).
There is a new management interface.
The googlemaps module uses the latest version 3 API.
There are some performance improvements and reduced memory requirements.

This is the first stable release of webtrees

The "trunk" series represents the primary line of development rather than a stable release branch. This is sometimes also called MAIN or HEAD.