renamed line number widget functions for consistency

all of these function were prefixed with 'lineNumberWidget'
minor cleanups and updated files for release 0.3.2

corrected a memory leak with the edit box instance
added void to the main window destructor argument list
removed unnecessary setting of ignore change flag in edit box
updated copyright year of affected files
updated README, rel_notes.txt and CMakeLists.txt for release 0.3.2