Segfault after clicking "Properties" in Soundlibrarypanel

reproducing the bug create a assertion `preDrumkitInfo' failed. i have write a small check for this case ( no soundlibrary loaded ). now, function SoundLibraryPanel::on_drumkitPropertiesAction() open a qmessage box with the error message 'The current loaded song missing his soundlibrary.Please load a existing soundlibrary', and return the function before soundlibrarypropertiesdialog call.

For the Properties dialog its important to have 2 soundlibrary informations. if you call the dialog from an not loaded soundlibrary the function have to load the soundlibrary at first, to get all informations and if needed make changes into the soundlibrary. after closing the dialog the old soundlibrary will reloaded.