When displaying properties for a directory, the PropertiesWindow now
shows: the total number of files, the total number of subdirectories,
and the total size of all files, in bytes.
These numbers are calculated on a background thread, and current
progress is displayed to the user every 100ms.
Otherwise, we end up propagating those dependencies into targets that
link against that library, which creates unnecessary link-time
dependencies.
Also included are changes to readd now missing dependencies to tools
that actually need them.
We previously put the generated headers in SOURCES, which did not mark
them as GENERATED (and did not produce a proper dependency).
This commit moves all generated headers into GENERATED_SOURCES, and
removes useless header SOURCES.
And display the progress of the copy operation in a separate window. :^)
Note that this patch only updates the drag&drop code path to use the new
mechanism. We still have to go through FileManager and make use of this
everywhere.
We also need to support additional operations, like Move, Delete, etc.
Still, this is quite cool! :^)
