Repurpose -v/--verbose; add -t/--terse option (repmgr only)

repmgr and particularly repmgrd currently produce substantial
amounts of log output. Much of this is only useful when troubleshooting
or debugging.

Previously the -v/--verbose option just forced the log level to
INFO. With repmgrd this is pretty pointless - just set the log
level in the configuration file. With repmgr the configuration
file can be overriden by the new -L/--log-level option.

-v/--verbose now provides an additional, chattier/pedantic level
of logging ("Opening *this* logfile", "Executing *this* query",
"running in *this* loop") which is helpful for understanding
repmgr/repmgrd's behaviour, particularly for troubleshooting.
What additional verbose logging is generated will of course a
also depends on the log level set, so e.g. someone trying to
work out which configuration file is actually being opened
can use '--log-level=INFO --verbose' without being bothered
by an avalanche of extra verbose debugging output.

-t/--terse option will silence certain non-essential output, at
the moment any HINTs.

Note that -v/--verbose and -t/--terse are not mutually exclusive
(suggestions for better names welcome).

log.h

@@ -121,8 +121,11 @@ bool		logger_init(t_configuration_options * opts, const char *ident,
 
 bool		logger_shutdown(void);
 
-void		logger_min_verbose(int minimum);
+void		logger_set_verbose(void);
+void		logger_set_terse(void);
+
 void		log_hint(const char *fmt, ...);
+void		log_verbose(int level, const char *fmt, ...);
 
 extern int	log_type;
 extern int	log_level;