Course project for Getting and Cleaning data (tidy dataset)

While working on the main function, I've split the main operations into individual functions and was doing my best to give descriptive names to them. I've also included in-line comments to better explain the sections of the code. Here is a summary of how it works:

Function name: loadTT

• it locates and downloads the "UCIDataset.zip" file from the url provided in the body of the main function and unzips it

Function name: mergeTT

• loads the test and training data into two separate data frames.
• binds the corresponding subjects' IDs provided within the "y_...txt" file with the corresponding data frame
• binds the rows from the train data frame with the rows of the test data frame and stores them into the mTidyData data frame

Function name: MeanStdColumns

• loads the list of features into a data frame
• subsets mTidyData by the columns whose names' contain either "mean" or "std" in their description
• adds the description of the subset features as column headers

Function name: CreateAvgbySubject

• using by SubjectID to apply mean to each measurement columns

Function name: WriteTabletoFile

• needless to explain.