Added sort() function and transpose() in Matrix class

[sakshichahal53]

Do the checklist before submitting the PR:

• [x ] Have you read the guidelines mentioned in CONTRIBUTING.md?
• [ x] Have you squashed your commits?

Q: What version of Node.js you've used in the project? (e.g. Node v10.11.0) A: v 8.15.0

Q: Mention the Issue Number! (e.g. Fixed #8) A: 152

• Give additional information regarding the PR below:

Sort a matrix [2-D array] can be called as : let obj = new M.Matrix(a); //here a is a 2-D array console.log(obj.sort('row'));

Transpose of a matrix can be called as: console.log(obj.transpose());

[codecov-io]

Codecov Report

Merging #155 into master will decrease coverage by 1.88%. The diff coverage is 7.4%.

@@            Coverage Diff             @@
##           master     #155      +/-   ##
==========================================
- Coverage     100%   98.11%   -1.89%     
==========================================
  Files          77       78       +1     
  Lines        1301     1328      +27     
==========================================
+ Hits         1301     1303       +2     
- Misses          0       25      +25

Impacted Files	Coverage Δ
src/validation/matrix-sort-type.js	33.33% <33.33%> (ø)
src/Matrix/index.js	72.28% <4.16%> (-27.72%)	:arrow_down:

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