Updated pixelWidth()

The input files have been classified into two types. InputFileRaw (one
containing the whole data), and inputFile (the one with cropped data).
Most of the analysis will be done on the cropped data, but the pixel
size will be calculated using the raw data file.
Changes in main()

Object hP will be created only if inputFile and inputFileRaw exist. If
not, a warning message is displayed.