Changes the icon rendering for the properties view "question mark" icon
from Qt label HTML to use the IconLabel widget. This makes the label
high DPI.
Unfortunately the properties view code is a complete nightmare and in a
way, this PR makes this worse by adding the "leftWidget" widget as a
placeholder for what the "normal" label used to be, but you can't easily
replace that label with the icon label (while retaining prior
modifications from other nightmare code) so here we are. The entire
thing needs to be burnt to the ground and be rebuilt from the ground up
but that's a task for another day.
When a source file contains an explicit include with a filename
following the "moc_<actual-filename>.cpp" pattern, then CMake's
AUTOMOC generation tool will recognize the matching pair and generate
the replacement header file and add the required include directory
entries.
For all files which do contain Q_OBJECT or similar declarations but do
not have an explicit include directive, the global mocs_compilation.cpp
file will still be generated (which groups all "missing" generated
headers).
The larger this global file is, the more expensive incremental
compilation will be as this file (and all its contained generated
headers) will be re-generated regardless of whether actual changes
occurred.
List widgets are currently used as playlists in source properties,
but only contain the file paths and no other identifying information.
This can lead to files being added multiple times, so when changes to
list order occurs, plugins cannot uniquely identify which duplicate
item was actually changed (because they're only identified by the path).
By adding a UUID to the user data role of a list item, an additional
unique information is added that allows plugins to de-duplicate list
items.
