log: Add support for slf4j-style parameterised logging

[jasraj]

Testing:

/ model name      : Intel(R) Core(TM) i7-8700 CPU @ 3.20GHz

/ Setup
q) .require.lib`log; .log.setLevel`DEBUG;
q) sym:`a;
q) dict:`a`b`c!1 2 3;
q) table:flip `a`b`c!2?/:(`3; 1f; 100j);

// Logging enabled
q) .log.info "A symbol: ",string sym;                                   / Old format
q) if[.log.isLoggingAt `DEBUG; .log.debug "A symbol: ",string sym ];    / Old with log level check
q) .log.info ("A symbol: {}"; sym);                                     / New (slf4j-style) format

// Logging disabled
q) .log.trace "A symbol: ",string sym;                                  / Old format
q) if[.log.isLoggingAt `TRACE; .log.trace "A symbol: ",string sym ];    / Old with log level check
q) .log.trace ("A symbol: {}"; sym);                                    / New (slf4j-style) format

Results:

Outputs	Format	Iterations	ts
YES	Old	1000	Atom: 32 4196240 Dict: 18 4195840 * Table: 118 4195904
YES	Old with check	1000	Atom: 36 4196496 Dict: 18 4196096 * Table: 115 4196160
YES	New	1000	Atom: 33 4195456 Dict: 21 4195344 * Table: 118 4195344
NO	Old	10000	Atom: 5 2336 Dict: 94 1808 * Table: 196 2464
NO	Old with check	10000	Atom: 12 3120 Dict: 11 2208 * Table: 12 2208
NO	New	10000	Atom: 2 1984 Dict: 2 1680 * Table: 2 1712

When the log level is output to standard out / standard error the performance of all 3 mechanism is more-or-less the same.

However, when the log level is disabled, there is a significant increase in performance with the new logging format, particularly if the object to be printed is a complex object (generally deferring to .Q.s1).