adds comments
removes calls to strlen
caches message properties
adds message body setter
Merge branch 'perf_opt_2'
removes check for bcmath extension since composer.json specifies it as a requirement
allows reusing AMQPReader object instances, since on long running process there could be quite a few created.

Current code creates 36k AMQPReader instances in order to consumer 4k messages
reuses AMQPReader inside AbstractConnection::wait_frame
removes tmp variable
avoids creating multiple AMQPReader instances
fixes parser for 091 extension support
standarises method names