Moving empty destructors out of the .cpp files and into headers
allows them to be devirtualized in certain cases.
(When the compiler can't "see" a function in a header, it must largely
assume it's some black box that the linker will resolve.)
While we're at it, use C++11's `= default` to define empty virtual
desturctors for us.
For some classes (e.g., Piano), nothing is derived from it, so we can
mark the class as final and remove any explicit virtual dtor.
There are many other places where this can be done, but this is a large
enough patch as-is.
Fixes 20 warnings similar to the following ones when generating a translation file with e.g. "make de.ts":
/home/daniel/Lmms/src/tracks/AutomationTrack.cpp:40: Class 'AutomationTrack' lacks Q_OBJECT macro
/home/daniel/Lmms/src/core/FxMixer.cpp:41: Class 'FxRoute' lacks Q_OBJECT macro
/home/daniel/Lmms/src/core/FxMixer.cpp:554: Class 'FxMixer' lacks Q_OBJECT macro
/home/daniel/Lmms/src/gui/widgets/MeterDialog.cpp:52: Class 'MeterDialog' lacks Q_OBJECT macro
...
Fixes 20 warnings similar to the following ones when generating a translation file with e.g. "make de.ts":
/home/daniel/Lmms/src/tracks/AutomationTrack.cpp:40: Class 'AutomationTrack' lacks Q_OBJECT macro
/home/daniel/Lmms/src/core/FxMixer.cpp:41: Class 'FxRoute' lacks Q_OBJECT macro
/home/daniel/Lmms/src/core/FxMixer.cpp:554: Class 'FxMixer' lacks Q_OBJECT macro
/home/daniel/Lmms/src/gui/widgets/MeterDialog.cpp:52: Class 'MeterDialog' lacks Q_OBJECT macro
...
The MIDI event handling in InstrumentTrack was complex and buggy. It has
been simplified now such that processInEvent() tries to handle note on,
note off and key pressure events. The actions taken should result in
equivalent calls to processOutEvent() by NotePlayHandle instances. The
processOutEvent() function sends according MIDI events to the attached
instruments. All unhandled MIDI events are directly forwarded to the
instrument in processInEvent().
It's possible that some corner-cases are not handled yet with the new code
and we have regressions now.
Furthermore renamed midiTime/midiEvent to MidiTime/MidiEvent to match
coding style.
Closes#72.
