Adding ghost checker

[elliotchance]

A bit of refactoring to enforce the default max line complexity of 5. This should be improved further in the future.

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This change is 

[codecov-io]

Codecov Report

Merging #160 into master will increase coverage by 1.17%.
The diff coverage is 56.33%.

@@            Coverage Diff             @@
##           master     #160      +/-   ##
==========================================
+ Coverage   41.37%   42.55%   +1.17%     
==========================================
  Files         135      138       +3     
  Lines        3705     3887     +182     
==========================================
+ Hits         1533     1654     +121     
- Misses       2147     2207      +60     
- Partials       25       26       +1

Impacted Files	Coverage Δ
dater.go	100% <ø> (ø)	⬆️
gedcom2html/main.go	0% <ø> (ø)	⬆️
gedcomdiff/main.go	0% <0%> (ø)	⬆️
html/table_cell.go	0% <0%> (ø)	⬆️
html/line_break.go	0% <0%> (ø)
gedcom2html/source_link.go	0% <0%> (ø)	⬆️
gedcom2html/family_statistics.go	0% <0%> (ø)	⬆️
html/table.go	0% <0%> (ø)	⬆️
gedcomdiff/individual_compare.go	0% <0%> (ø)	⬆️
gedcom2html/util.go	0% <0%> (ø)	⬆️
... and 52 more

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