Create palindrome.c

This C program includes three different ways of checking for palindromes. 
1. Palindrome - calculating the length of the string, checking index[0] with index[size-1]. 
2. PalindromeXOR() - calculating the length of the string, checking index[0] with index[size-1].
3. PalindromeNoSize() - using XOR on the whole string - Fastest way