add default arg constructors, and test all constructors

[rafaqz]

What the pull request does
Adds arg constructors with defaults where there is more than one argument.

And test all constructors (please check that I got them all!!)

Type of change
Please indicate the relevant option(s)

• [x] :bug: Bug fix (non-breaking change which fixes an issue)
• [ ] :sparkle: New feature (non-breaking change which adds functionality)
• [ ] :boom: Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] :book: This change requires a documentation update

Checklist

• [x] The changes are documented
  • [ ] The docstrings of the different functions describe the arguments, purpose, and behavior
  • [ ] There are examples in the documentation website
• [x] The changes are tested
• [x] The changes do not modify the behavior of the previously existing functions
  • If they do, please explain why and how in the introduction paragraph
• [ ] For new contributors - my name and information are added to .zenodo.json
• [ ] The Project.toml field version has been updated
  • Change the last number for a v0.0.x series release, a bug fix, or a performance improvement
  • Change the middle number for additional features that do not break the current test suite (unless you fix a bug in the test suite)
  • Change the first number for changes that break the current test suite

[codecov-io]

Codecov Report

Merging #52 (709e238) into main (8b84f18) will increase coverage by 27.28%. The diff coverage is 100.00%.

@@             Coverage Diff             @@
##             main      #52       +/-   ##
===========================================
+ Coverage   61.56%   88.85%   +27.28%     
===========================================
  Files          14       14               
  Lines         268      296       +28     
===========================================
+ Hits          165      263       +98     
+ Misses        103       33       -70     

Flag	Coverage Δ
unittests	88.85% <100.00%> (+27.28%)	:arrow_up:

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/algorithms/nnelement.jl	95.23% <ø> (+0.79%)	:arrow_up:
src/algorithms/nncluster.jl	100.00% <100.00%> (+100.00%)	:arrow_up:
src/algorithms/perlinnoise.jl	92.06% <100.00%> (+2.40%)	:arrow_up:
src/algorithms/rectangularcluster.jl	100.00% <100.00%> (ø)
src/algorithms/wavesurface.jl	100.00% <100.00%> (ø)
src/algorithms/edgegradient.jl	100.00% <0.00%> (ø)
src/algorithms/diamondsquare.jl	100.00% <0.00%> (ø)
src/algorithms/planargradient.jl	100.00% <0.00%> (ø)
... and 7 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update 8b84f18...709e238. Read the comment docs.