Clean up `MusicScale` class

[mself]

• Make MusicScale objects immutable
  • Expand constructor to initialize all members
• Use std::vector instead of Array1d
• Move initialization of class from musicnotes.cpp to static init() method
• Convert g_music_scales from global variable to private static member with accessor method
• Add helper methods isChromaticScale, isMinorScale, isMajorScaleNote, and isCompatibleWithTemparament to remove business logic from UI layer
• Change GData::m_music_key_type from int to MusicScale::ScaleType
• Remove logic from GData::setTemperedType() that removes and inserts items from the key types combo box
• Replace MainWindow::remove_key_type() and MainWindow::add_key_types() with MainWindow::updateKeyTypes()
• Connect the temperedTypeChanged signal to MainWindow::updateKeyTypes() to update the combo box items when the tempered type is changed

[quicky2000]

thansk!