PR for v.1.3.7

[hcpchris]

• BUGFIX: Fixed bug in HighchartsMeta.copy() (copy() method raises an error when creating options instance from from_js_literal() #98).
• BUGFIX: Fixed bug in data point serialization to primitive array.

[codecov]

Codecov Report

Merging #100 (7ff526b) into master (f38969a) will increase coverage by 0.04%.
Report is 3 commits behind head on master.
The diff coverage is 33.33%.

@@            Coverage Diff             @@
##           master     #100      +/-   ##
==========================================
+ Coverage   90.28%   90.32%   +0.04%     
==========================================
  Files         206      206              
  Lines       28180    28184       +4     
  Branches     1948     1950       +2     
==========================================
+ Hits        25442    25457      +15     
+ Misses       2000     1982      -18     
- Partials      738      745       +7     

Files Changed	Coverage Δ
highcharts_core/metaclasses.py	65.30% <20.00%> (+2.43%)	⬆️
highcharts_core/js_literal_functions.py	70.93% <100.00%> (ø)