Created files to hold helper functions for imw files, and implemented
function to read an imw file.

	 * src/ImwHelper.cc: New.
	 * src/ImwHelper.hh: New.
	 * CMakeLists.txt: Take the new file to compilation.
Added a method to convert a CV_16U image to a CV_8U image.

Conversion works by putting the values from the range [0, mu + 3 sigma]
to [0, 255].
	* src/ImwHelper.cc: Here.
	* src/ImwHelper.hh: Here.