Parallel matrix multiplication algorithm added

[HarsheetKakar]

References to other Issues or PRs or Relevant literature

Fixes #239

Brief description of what is fixed or changed

Other comments

Not sure on the implementation for DODA yet, further discussion is needed

[codecov]

Codecov Report

Merging #241 into master will increase coverage by 0.010%.
The diff coverage is 100.000%.

@@              Coverage Diff              @@
##            master      #241       +/-   ##
=============================================
+ Coverage   98.564%   98.575%   +0.010%     
=============================================
  Files           24        24               
  Lines         2090      2106       +16     
=============================================
+ Hits          2060      2076       +16     
  Misses          30        30               

Impacted Files	Coverage Δ
pydatastructs/linear_data_structures/__init__.py	100.000% <ø> (ø)
pydatastructs/linear_data_structures/algorithms.py	100.000% <100.000%> (ø)

[czgdp1807]

For DODA if a single None is found, an automatic TypeError would be raised, so we do not have to worry about Nones. More discussion on the patch later today.

[HarsheetKakar]

shall I move the helper function in the function itself?