add rudimentary audio plotting functionality
bump Qt and KF versions
add function for calculating rms over time (sliding window)
use KPageWidget
fixup licensing
minor refactoring
use _s operator rather than QStringLiteral macro
add rms function
update generate_signal
use struct to hold sound file data
add calculator page
add rudimentary impulse response page
add closeCurrentPage action

the list item should be removed before the page so the indexes do not
get out of sync. Since QListWidget::currentRowChanged is connected to
QStackedWidget::setCurrentIndex, when the list item gets removed, the
index for both list and stack get changed from the index that will get
removed. Then when the page gets removed the stack index does not need
to change.
add rudimentary page list
add skeleton openFile action
put fileListModel in App
start implementing a model to keep track of open files (not functional yet)
reassign mainPage rather than pushing more pages
remove signal generator from UI

found other options for generating sweeps and impulse responses (Aliki and LSP Plugins Profiler)