Fix save

[evadelmas]

Fixes #93

Summary of changes:

1. Updates dependencies
2. save now uses jld2
3. model parameters that are functions are saved as string(p[:...])

[coveralls]

Coverage increased (+1.8%) to 90.046% when pulling 746eae1 on fix-save into 92a6a7c on next.

[codecov]

Codecov Report

Merging #94 into next will increase coverage by 0.16%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##             next      #94      +/-   ##
==========================================
+ Coverage   89.98%   90.14%   +0.16%     
==========================================
  Files          16       16              
  Lines        1068     1086      +18     
==========================================
+ Hits          961      979      +18     
  Misses        107      107

Impacted Files	Coverage Δ
src/BioEnergeticFoodWebs.jl	100% <ø> (ø)	⬆️
src/measures.jl	49.23% <100%> (+8.15%)	⬆️

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