Finalize removal of liblog4cxx dependency

[bchretien]

This follows the work done in roboptim/roboptim-core#120.

[coveralls]

Coverage remained the same at 78.876% when pulling 8b77850 on bchretien:feat/log4cxx-removal into 2e04f69 on roboptim:master.

[coveralls]

Coverage remained the same at 78.876% when pulling 8b77850 on bchretien:feat/log4cxx-removal into 2e04f69 on roboptim:master.

[coveralls]

Coverage remained the same at 78.876% when pulling 8b77850 on bchretien:feat/log4cxx-removal into 2e04f69 on roboptim:master.

[codecov-io]

Codecov Report

Merging #38 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #38   +/-   ##
=======================================
  Coverage   74.87%   74.87%           
=======================================
  Files          10       10           
  Lines         398      398           
  Branches       49       49           
=======================================
  Hits          298      298           
  Misses         63       63           
  Partials       37       37

Impacted Files	Coverage Δ
src/tnlp.hxx	66.19% <ø> (ø)	⬆️
src/tnlp.hh	100% <ø> (ø)	⬆️

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[coveralls]

Coverage remained the same at 78.876% when pulling fdc20ea on bchretien:feat/log4cxx-removal into 2e04f69 on roboptim:master.

[coveralls]

Coverage remained the same at 78.876% when pulling 4466b72 on bchretien:feat/log4cxx-removal into 2e04f69 on roboptim:master.

[florent-lamiraux]

Is it possible to merge this pull request in order to be able to merge PR#40 in roboptim-trajectory?

[bchretien]

@florent-lamiraux I wanted to solve the AppVeyor issue back then but never found the time, I guess the Windows build will fail until I find the motivation. Merged!