Reduce tolerance when creating cells via contourCoordinate in chordwise direction

[svengoldberg]

This fix is related to PR #1026 and the belonging issue #933.
In the named PR, the tolerance was only reduced in spanwise direction. This PR also adds the reduction for the chordwise direction to fix cell overlap in the other direction.

Checklist:

• A test for the new functionality was added.
• All tests run without failure.
• The new code complies with the TiGL style guide.
• New classes have been added to the Python interface.
• API changes were documented properly in tigl.h.
• Changes were documented in tigl/ChangeLog.md

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 69.47%. Comparing base (10a7fcf) to head (dfa06d8).
Report is 3 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1034   +/-   ##
=======================================
  Coverage   69.47%   69.47%           
=======================================
  Files         301      301           
  Lines       26889    26889           
=======================================
  Hits        18681    18681           
  Misses       8208     8208           

Flag	Coverage Δ
unittests	69.47% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
src/wing/CCPACSWingCell.cpp	77.98% <100.00%> (ø)