fix #4443: implement flexible chord entry system
fine tune chord parser, fix chord editing to use last chordname
initial text for chord edit: first name field of last XML file (rather than last name field)
allow trailing ctrl-space in chordname to suppress parsing
Play Panel: persistent size and pos across sessions

*) Size and pos are read from QSettings when the widget is created
*) Size and pos are stored to QSettings when the widget is hidden/closed/destroyed
*) The member var Preferences::playPanelPos is removed, as the play panel pos is not configurable in preferences
Fixing rebase artifacts!
Merge pull request #337 from MarcSabatella/4443-flexible-chord-names

4443 flexible chord names
Merge pull request #326 from mgavioli/PlayPanel_persistent_size_pos

Play Panel: persistent size and pos across sessions
add comment in chordlist.cpp