Enhancement in sorting algorithms

[czgdp1807]

References to other Issues or PRs or Relevant literature

Brief description of what is fixed or changed

Sorting algorithms now do not disturb positions which are out of scope of start and end. None is treated is infinite value. A custom comparator is introduced for the same.

ping @HarsheetKakar

Other comments

.. [1] #207 (comment)

[codecov]

Codecov Report

Merging #216 into master will increase coverage by 0.020%.
The diff coverage is 100.000%.

@@              Coverage Diff              @@
##            master      #216       +/-   ##
=============================================
+ Coverage   96.876%   96.897%   +0.020%     
=============================================
  Files           24        24               
  Lines         1921      1934       +13     
=============================================
+ Hits          1861      1874       +13     
  Misses          60        60               

Impacted Files	Coverage Δ
pydatastructs/linear_data_structures/algorithms.py	100.000% <100.000%> (ø)
pydatastructs/linear_data_structures/arrays.py	100.000% <100.000%> (ø)
pydatastructs/utils/misc_util.py	90.740% <100.000%> (+0.740%)	⬆️

[HarsheetKakar]

Thanks it makes work a lot easier

[HarsheetKakar]

Can we change None to another Node type so that we can overload its operators which will remove the need for _comp.