This lays down some groundwork for realtime gestures in Wayland,
so that gestures that are 1:1 with user motion on a touchpad are
now possible to implement.
Due to earlier commits, this is mostly just glue code to make a
convenient API.
Gestures implemented with this API are four-finger gestures, to
avoid conflicting with apps that may use two or three-finger
gestures.
I consider this a prerequisite commit to improving the quality of touchpad gestures provided by KWin.
In short, this breaks apart a weird all-in-one class into an std::variant for the different types
of shortcuts in order to make it easier to add new types of global shortcuts. For the byte shavers, this
roughly halves the size of the GlobalShortcut class as well. On top of all this, the code is about half
the size it was before, mostly due to newer C++ concepts being used that allow us to let the compiler
do more work for us.
Once in a while, we receive complaints from other fellow KDE developers
about the file organization of kwin. This change addresses some of those
complaints by moving all of source code in a separate directory, src/,
thus making the project structure more traditional. Things such as tests
are kept in their own toplevel directories.
This change may wreak havoc on merge requests that add new files to kwin,
but if a patch modifies an already existing file, git should be smart
enough to figure out that the file has been relocated.
We may potentially split the src/ directory further to make navigating
the source code easier, but hopefully this is good enough already.
