libappfw|UI|Performance: Only use blurring when Style allows

Blurring is still quite heavy when the map renderer is drawing in
the background. Currently Style only allows popup background blurring
in the Home screen.
Performance|Client: Faster resizing of the view

When the view grid was updated, LensFX was always releasing all GL
resources for all viewports even if the viewports were only resized.
Fixed|ScrollWidget|libappfw: Scrolling speed with HiDPI

Scrolling is done in device pixels, while mouse input is independent
of HiDPI.
Fixed|libcore|Variable: Notification about value changes

The ChangeFrom audience was being ignored if there wasn't regular
Change audience members.
Fixed|libcore|Record: Assignment causes notifications about members

Previously no notification was made about new members when members
were copied from another record.
Fixed|libdoomsday|DEDRegister: Handling initially empty lookup key values

If a lookup key is not given a value when initially added, it will
still be observed so that when the value is given, it will be added
to the appropriate lookup.

However, this assumes that only the latest record is being modified
(otherwise the lookup may not point to the correct entry).
Fixed|libdoomsday|DED: Indexing copied model definitions

When making a copy of an existing definition, omit the lookup
identifiers to avoid messing up the indexing in DEDRegister.

Todo: DEDRegister should provide a method for copying, to hide this
implementation detail.
Cleanup
Refactor|libdoomsday|DED: Making copies of definitions

DEDRegister now provides a method for making a copy of an existing
definition so that all the appropriate members are excluded from the
copy.
Windows|Fixed|libdoomsday: Export template specializations

Thinker::MemberDelegate is a transitional utility, but for now it needs
to be exported manually when using MSVC.