* This version finalizes the separate command line interface (CLI) that can be used for developing shell and desktop applications
* A very important "under the hood" feature is the streams API
* This iteration of the build system, among other things, replaces the slow recursive make with one global Makefile and eases the integration of proper dependencies
* GD library is now bundled with the distribution and it is recommended to always use the bundled version
* Vpopmail and cybermut extensions are moved to PECL
* Several deprecated extensions (aspell, ccvs, cybercash, icap) and SAPIs (fastcgi, fhttpd) are removed
* Various security fixes (imap, mysql, mcrypt, file upload, gd, etc)
* Apache2 filter is improved, but is still considered experimental
* Significant improvements in dba, gd, pcntl, sybase, and xslt extensions
* Zend Engine has some fixes and minor performance enhancements
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