Implement logging infrastructure.

[1uc]

Implements basic logging infrastructure for human readable amounts of messages. The design idea is that any user of HighFive can optionally specify a backend logger by registering a callback.

The logging API consists of:

HIGHFIVE_LOG_{DEBUG,INFO,WARN,ERROR}(message)
HIGHFIVE_LOG_*_IF(cond, message)

The former forwards the message with the appropriate log severity along with the filename and line number to the logging callback. The latter does so only if the if-statement is true. It's important to avoid any side effects in cond since the macro might expand to a no-op if the compile time minimum log severity is too high. Therefore, cond wont be evaluated and the side effects wont happen.

Future work could add additional more advanced features. Alternatively, users that wish to have more advanced features could register an backend logging library that supports the desired features.

[codecov-commenter]

Codecov Report

Merging #690 (f2352b9) into master (4d29dee) will increase coverage by 0.24%.
The diff coverage is 88.88%.

@@            Coverage Diff             @@
##           master     #690      +/-   ##
==========================================
+ Coverage   81.16%   81.40%   +0.24%     
==========================================
  Files          67       67              
  Lines        4151     4244      +93     
==========================================
+ Hits         3369     3455      +86     
- Misses        782      789       +7     

Impacted Files	Coverage Δ
include/highfive/bits/H5Object_misc.hpp	89.74% <0.00%> (ø)
include/highfive/bits/H5ReadWrite_misc.hpp	73.33% <66.66%> (+4.58%)	⬆️
include/highfive/H5Utility.hpp	78.04% <72.72%> (-21.96%)	⬇️
tests/unit/tests_high_five_base.cpp	99.61% <100.00%> (+0.01%)	⬆️

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