Previously, the only way to access the rules list was via
the `rules()` and `setRules()` methods, so the actual
settings objects were not accesible.
This commit adds methods to retrieve, insert, remove or reorder
the rules within the list.
Since every individual rule is stored as a KConfig group, and
they are not designed to be dynamically renamed, using consecutive
numbered groups and store only the total count is problematic.
So we also add a new stringlist setting to store the rules group
names and their order.
Now any group name is valid. To avoid collisions use random QUuids
as group names for newly created rules.
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.
