Add string matching Algorithms for multiple programming languages.

[thecodershub]

• Simple substring check
• KMP algorithm
• Z algorithm

Please mention programming language and algorithm you're going to work in your claim here. Mention issue in pull request.

[DheerendraRathor]

I'm going to work on Z-algo in python

[CaffeinatedCat0]

I'll work on simple substring check in python

[shrawnz]

I'll work on simple substring check in c++

[vaarsha]

I will work on simple substring check in c

[thecodershub]

To all the contributors, please add tests and read the contribution guide before sending PRs.

[manrajgrover]

Working on Simple Substring Check for Php, JavaScript and Java.

[manrajgrover]

@thecodershub Are we allowed to use in built functions?

[thecodershub]

@manrajgrover Yes. In that case add multiple methods - one with built in function and one without them.