Rework tick_msg() to make messages displayed during startup more

Rework tick_msg() to make messages displayed during startup more
reliable and consistant.

Eliminate unused time_t parameter since we only tick during the first
link_timeout seconds. Replace it with 'action' parameter to clearly
indicated what tick_msg() is supposed to do.

Fix issuance of '\n' before log_debug() messages. Properly
reinitialize static variables.

Use more precise 'timespec' timers, hewing to idiom suggested by
cheloha@.