Coherent return types for Kruskal and Prim

[aurorarossi]

Now both algorithms return a Vector{Edges}. I chose Vector{Edges} instead of Vector{SimpleWeightedEdge} because in this way the code is faster. In the case that weights are needed it is easy to query them.
Issue #130

[codecov]

Codecov Report

Merging #172 (c5b378f) into master (a3fb98b) will not change coverage.
The diff coverage is 100.00%.

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##           master     #172   +/-   ##
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  Coverage   97.54%   97.54%           
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  Files         109      109           
  Lines        6314     6314           
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  Hits         6159     6159           
  Misses        155      155           

[aurorarossi]

@matbesancon

[simonschoelly]

Hey Aurora, thanks for your PR.

While it might be a very good idea, to return the same types from both algorithms, changing that now would break existing code, so we rather do this when we bump the mayor version to v2.0.

[aurorarossi]

Ok thanks @simonschoelly !