add missing dependency
pass all possible values at instanciation
more consistency with HTTP::Client
no need to store timeout twice
those are methods, not functions...
fix signal handlers

- CTRL+C send SIGINT, not SIGTERM
- pseudo-signal for fatal error is __DIE__
- signal handlers have to call exit() or die() to ensure termination
fix options list in synopsis
add microsoft vendor id
more logical log messages

let's use 'info' priority for what the agent does, and 'debug' priority
for what it doesn't.
more consistent thread id in log messages
drop another model artefact
no need for perl line number in message
remove unwanted line number at the source
stop decoding immediatly after first null byte
decode hex-encoded strings in LLDP info

see: #2670,#2746,#2754
decode hex-encoded strings in CDP info

see: #2670,#2746,#2754
don't duplicate remote mac address uselessly
ignore empty sysname value in LLDP info
ignore empty ifdescr value in LLDP info
skip earlier if required