Merger sort: First commit
[Development/Enhancement/Defect]
Development

[Description]
Merge sort implementation.

[Change]
merge_sort() and main() added.

[Test]
Compilation successfull.
Merge sort: Error during merging
[Development/Enhancement/Defect]
Defect

[Description]
During merging, the while loop condition expects index2 as -1. It
was set to -2.

[Change]
index2 is now being set at -1.

[Test]
Successfull compilation
Sorting worked successfully for different inputs.