Adds a type spec in the #lpdb{} record.
Refactor drop / lose message code + tests.
Adds logplex_msg_buffer:from_list/1.
Adds logplex_msg_buffer:resize/2 + tests.
Fix implementation of displace/2.
More dialyzer friendly versions of drop/lose.
Adds tcpsyslog resize_msg_buffer/2.
Makes tcpsyslog drain send size configurable.
Merge branch 'v55' into v56

Conflicts:
	src/logplex.app.src
Adds an old v55 to current v55 live upgrade.
Merge branch 'v55' into v56