getDataFiles: Merge multiple data files
In Cogitos/predata: Predata load data and explore them

Load multiple csv files into a unique data frame. A function to load all csv files within a given directory and merge data into a unique data frame.

1 2	getDataFiles(folder, targetCol = NULL, separator = ";", toSkip = 0, rowToRead = -1, addSubj = NULL)

`folder`	A string indicating the relative path of the folder in which are stored the csv files
`targetCol`	A vector of numbers to precise which columns should be read. Defaults to all columns.
`separator`	A string indicating the symbol use to differentiate the columns (, ; \t). Defaults to ";".
`toSkip`	A number to indicate how many lines (rows) should be ignored before reading the file. Defaults to 0.
`rowToRead`	A number to indicate how many lines (rows) should be read from the starting reading line. Defaults to all lines.
`addSubj`	Either a vector of 2 numbers to indicate the first and last character index of the csv file name to extract the subject name or a boolean index to TRUE to add a subject number equal to the process order of the file. Defaults to NULL to indicate that a subject identification is present.