kimagecache.h

[Alex Merry]

Another decision to be made :-)

kimagecache.h, in KGuiAddons, includes the template class
KSharedPixmapCacheMixin and the line
#define KImageCache KSharedPixmapCacheMixin<KSharedDataCache>

Using KImageCache will clearly not work without the header that defines
KSharedDataCache, which is in kcoreaddons.  Currently, this means users
of KImageCache have to include ksharedatacache.h as well as
kimagecache.h, which is less than ideal.

There are three possible solutions that I see to this:
1. just #include <kshareddatacache.h> in kimagecache.h, on the basis
KImageCache is useless without linking against KCoreAddons anyway

2. do some CMake magic to only do (1) if the current target is linked to
KF5::CoreAddons

3. move KImageCache to another framework that depends on KCoreAddons

Bear in mind that we can put KSharedPixmapCacheMixin its own header if
we actually think it might be useful independent of KSharedDataCache.

I would argue against (2), on the basis that it would break things for
any users that do not use CMake, and that sort of magic is fairly
fragile.  (1) is, I think, a better solution than (2).

aacid has advocated (3) (see http://git.reviewboard.kde.org/r/114478/),
although we would have to figure out *which* framework to put it in.

What do you think is the best solution?

Alex