Adding unit tests for sorting functions, and improving readability on some sorting algorithms (#784)

* Adding variable to fade out ambiguity

* More readability on merge sorting algorithm

* Updating merge_sort_fastest description and explaining why

* Adding tests file with imports

* Standardazing filenames and function names

* Adding test cases and test functions

* Adding test loop

* Putting 'user oriented code' inside main condition for having valid imports

* Fixing condition

* Updating tests: adding cases and todo list

* Refactoring first euler problem's first solution

project_euler/problem_01/sol1.py

@@ -10,8 +10,4 @@ try:
 except NameError:
     raw_input = input  # Python 3
 n = int(raw_input().strip())
-sum=0
-for a in range(3,n):
-    if(a%3==0 or a%5==0):
-        sum+=a
-print(sum)
+print(sum([e for e in range(3, n) if e % 3 == 0 or e % 5 == 0]))