Added Trie Data Structure

[czgdp1807]

References to other Issues or PRs or Relevant literature

Closes #229

Brief description of what is fixed or changed

Other comments

[codecov]

Codecov Report

Merging #299 into master will increase coverage by 0.038%.
The diff coverage is 100.000%.

@@              Coverage Diff              @@
##            master      #299       +/-   ##
=============================================
+ Coverage   98.789%   98.827%   +0.038%     
=============================================
  Files           23        25        +2     
  Lines         2809      2901       +92     
=============================================
+ Hits          2775      2867       +92     
  Misses          34        34               

Impacted Files	Coverage Δ
pydatastructs/utils/__init__.py	100.000% <ø> (ø)
pydatastructs/__init__.py	100.000% <100.000%> (ø)
pydatastructs/strings/__init__.py	100.000% <100.000%> (ø)
pydatastructs/strings/trie.py	100.000% <100.000%> (ø)
pydatastructs/utils/misc_util.py	100.000% <100.000%> (ø)

[czgdp1807]

Will be merged if no objections raised for 24 hours.