corrected bugs when applying window functions

Signed-off-by: Maximilian Güntner <maximilian.guentner@gmail.com>
refactored some functions

Signed-off-by: Maximilian Güntner <maximilian.guentner@gmail.com>
added install target

Signed-off-by: Maximilian Güntner <maximilian.guentner@gmail.com>
refactored some functions, mostly camelCase

Signed-off-by: Maximilian Güntner <maximilian.guentner@gmail.com>
improved beat detection a bit

Signed-off-by: Maximilian Güntner <maximilian.guentner@gmail.com>
added windowFunction comboBox

Signed-off-by: Maximilian Güntner <maximilian.guentner@gmail.com>