Fix for #215 and some other related improvements

- Replaced AMQPWriter chrByteSplit() & byteSplit() with more reliable and ~35% more effective packBigEndian(), which also supports negative numbers
- Fixed #215 and some other issues on 64bit
- Added support for signed longlong, some perf optimizations
- Improved existing and added absent range checks, fixed write_long() with vals >php_int_max on 32bit
- Fixed existing and added new tests, highly increased num of iters
- Reformatted the code for better readability
- Reverted int values to be encoded as long in write_array(), as longlong not supported in AMQP-0.8
- fixed exception msg in test
- Fixed #216. Added wrapper/helper classes AMQPArray & AMQPTable, which may be directly passed to AMQPWriter::write_array() & write_table()
- examples now use AMQPTable
- Fixed 'b' type to be read as short-short-int, as per amqp spec.
- Added few data types
- made read_value() private, just like its counterpart write_value()
- Took care of field types mess - http://www.rabbitmq.com/amqp-0-9-1-errata.html#section_3
- By default rabbitMQ set is used
- reverted Decimal to use signed long as per http://www.rabbitmq.com/amqp-0-9-1-errata.html#section_3
- removed unused ArrayAccess iface from AMQPAbstractCollection
- Incoming message headers as AMQPTable, easily retrievable in their original form via getNativeData()
- Added examples for message headers
- fixed test for 32bit systems
- added full void (null) support
- adapted to prev changes (message application_headers is now AMQPTable instance)
- fixed assertEquals sematic to conform ($expected, $actual)
- fixed setUp() was affecting global state causing consecutive tests to fail
- Changed some methods to accept empty $arguments to make them friendly to downstream type-hinted wrappers like someMethod($foo, $bar, AMQPTable $args=null) {basicConsume(...., $args);}
- fixed tests to pass on Travis's ancient phpunit version