Require PHP 5.3

[JDGrimes]

As of today, Travis CI has removed PHP 5.2 support. The result is that we can no longer support PHP 5.2 without an undue burden that will negatively affect the experience of most of our users.

I propose that we drop PHP 5.2 as quickly as possible. However, I think we should make 5.3 only a recommendation in 1.x, but a requirement with 2.x. In other words, we'll hold off on using any of the features from PHP 5.3 until 2.0.0.

This is not new territory, and I've previously calculated that WordPress and PHP 5.2 probably have only another year together anyway. Currently the stats show that PHP 5.2 is at 32.1%.

I've searched for plugins that require 5.3, and here are some:

• Constant Contact API (~115,000 downloads)
• Background Manager (~185,000 downloads)
• Akeebaback Update Core (~39,000 downloads)
• Ninja Firewall (~26,000 downloads)
• Stream (~37,000 downloads)

You get the idea.

[JDGrimes]

See travis-ci/travis-ci#3152.

If 5.2 comes back on Travis, we'll continue to support it as long as WordPress does. So we won't start doing anything explicitly 5.3, even in 2.0.

The plan is now this: we'll remove 5.2 from our .travis.yml for now. If it comes back, we'll add it back in. If it doesn't come back before 1.10 is released, we'll begin recommending at least 5.3. After that we will probably not walk it back even if Travis CI restores 5.2 temporarily.

[JDGrimes]

Travis has re-instated PHP 5.2. We'll continue to support it as long as WordPress does, unless barring any unforeseen changes.