PR for v.1.3.2

[hcpchris]

• BUGFIX: Fixed incorrect handling when defining a new Exporting.buttons context button under a different key name than contextButton. (Closes Exporting buttons get dropped #84 )

[codecov]

Codecov Report

Merging #85 (2595ea9) into master (0280157) will decrease coverage by 0.18%.
Report is 1 commits behind head on master.
The diff coverage is 21.25%.

@@            Coverage Diff             @@
##           master      #85      +/-   ##
==========================================
- Coverage   90.50%   90.32%   -0.18%     
==========================================
  Files         206      206              
  Lines       27854    27932      +78     
  Branches     1889     1922      +33     
==========================================
+ Hits        25208    25229      +21     
- Misses       1932     1982      +50     
- Partials      714      721       +7     

Files Changed	Coverage Δ
highcharts_core/metaclasses.py	60.21% <20.25%> (-6.55%)	⬇️
highcharts_core/utility_classes/buttons.py	84.88% <100.00%> (ø)