Fix: add navigation support to history

[molefrog]

• Makes sure the history.back() / go() ... methods are supported.
• Replaces replaceHistory with pushHistory.
• Rewrites a few specs

[codecov-io]

Codecov Report

Merging #25 into master will increase coverage by 0.78%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #25      +/-   ##
==========================================
+ Coverage   95.27%   96.06%   +0.78%     
==========================================
  Files           5        5              
  Lines         127      127              
  Branches       26       26              
==========================================
+ Hits          121      122       +1     
+ Misses          5        4       -1     
  Partials        1        1

Impacted Files	Coverage Δ
history.js	100% <100%> (ø)	⬆️
index.js	94.54% <100%> (+1.81%)	⬆️

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