Libraries should not use assert()
Added checks for a lot of previously-ignored return values
Explicitly pass and check buffer arg sizes

Also reduced use of some hardcoded buffer sizes, and made some return value conventions more consistent.
Fix to only read exact response length regardless of supplied buffer size for some requests
Substantially revamped the debugging system.
Clean up a bunch of misc compiler warnings
Perform sleep only when response is garbled, not every time
Reworked flushing/clearing and exchange_cmd to be more reliable

Made omron_send_clear more resilient
Created omron_flush to help resynchronize after errors
Removed infinite-loop possibility in omron_exchange_cmd
Added timeouts to win32 IO operations
Cleanup a bunch of unused/unneeded members/code.
Added omron_strerror() function
Streamlined get_command_response. Added PROTO debugging level.
Fix a reference to _is_inited which was missed before.