Drop support of too old PHP versions

5.6 sounds too much
mwhitney - I agree that many sites are using < 5.3 but those sites are old and there is no development.

As you all know PHP development started work over PHP 7.0, so there must be a lot of planning with the next major and the one after it.
CI 3.0 is almost in Final so it will kee current minimum at 5.2.x.
The first major after CI 3.0 may be build in with the powers of PHP 5.4.
Just refactorization of the framework to use Namespaces and perhaps Traits will take a huge amount of time.

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