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