Merge pull request #11 from remicollet/master

Fix test for PHP 5.4
Simple test tune.
Add explicit return checks.

Basically a manual merge of https://github.com/igbinary/igbinary/pull/16
before alocator changes.
Fix failing test and add one.
Compile and test without sessions.

See https://github.com/igbinary/igbinary/pull/14 by Ivan Shalganov.
Add simple and remove ol benmarking scripts.
Use a faster hash function
Prevent an extra copy of the serialisation buffer to be made.
Allow a different memory management strategy in case there is already allocated memory.
Realloc buffer at end of serialization to the real size.

Also, avoid extra copy in serssion serialization.