Changes:
- added new facility of tiered logging
- reviewed/refined tiers of all logged messages
- expanded the CLI option '-l' to '-l level'
- expanded the function of dynamically switching logging tiers through HTTP
- expanded display of counter 'log' on servstats page
- cleaned up further logics/codes in socket handler
- fixed measurement of POST processing time
For more details, go to https://kazoo.ga/pixelserv-tls/