Deprecate PHP 5.3 and test against PHP 5.5

[hjr3]

PHP 5.3 is end of life. I vote we tag php-5.3 which maintains PHP 5.3 support and break BC.

[baldurrensch]

Agreed.

[DannyvdSluijs]

I'm always a bit confused on why these remarks are deemed valid. I understand that from aPHP perspective it is EOL. However when looking from an OS perspective Ubuntu 12.04 which has PHP 5.3.10 installed from the Main. Ubuntu 12.04 LTS still is supported from April '17. I going out on limb that the probably are other distributions as well.

I would very like to change my production environments but can't. Is there a great benefit to no longer support 5.3.10 ?

[hjr3]

We can still support 5.3.10. I want to tag a branch for 5.3 and master would break 5.3 support. The reason this came up was because issue #14 was asking for JSON_PRETTY_PRINT support, which is available when >= 5.4.0.

I was going to use semver to increase the major version number, so anyone working on with 5.3.x would be unaffected.