as KLib is now also on github, the folder-structure has changed.
adjusted code to fit the new folder-structure where KLib resides
within the lib folder of the project.
added _build folder to gitignore

as requested by vobject: gui-controls now support the mouse-wheel

added -Wall -Wextra -pedantic to build-settings
fixed some compiler warnings
added TODOs for audio-samples and multiple channels

added workspace settings (like beats per minute) to load/save actions
fixed sequencer listeners, added sanity checks for add (already present) and checked propper remove on delete

created ifdef to exclude optional libfftw3 from MasterTarget