Provide defaults values for amqp_login

Provide default values for:
 - channel-max as AMQP_DEFAULT_CHANNEL_MAX 0 = unlimited
 - frame-size as AMQP_DEFAULT_FRAME_SIZE 131072 = 128KB
 - heartbeat as AMQP_DEFAULT_HEARTBEAT 0 = disabled
Add compile and runtime library version functions
Document public API
FIX: bring autotools build system up to date

Remove the amqp_framing.c/.h regeneration logic as it breaks make dist.
Bring the EXTRA_DIST list up to date with whats in the repo