[Marble-devel] Simplified builds: Adding marble-qt

[Dennis Nienhüser]

Hi,

currently we build the Desktop version bin/marble either as a KDE or a
Qt version based on the QTONLY cmake switch. This has a couple of drawbacks:
- it confuses newcomers
- it's not immediately clear which version you have on disk (you have to
run ldd on it or execute it)
- distributions/packagers can not build both versions in one go
- we break the build of the currently not active target regularly

To improve that I'd like to propose these changes:
- Reduce the QTONLY switch usage in src/lib as much as possible (ideally
the lib is identical regardless of the QTONLY setting)
- Build and install the Desktop Qt version always, and name it bin/marble-qt
- Build and install the Desktop KDE version if KDE libs are found, name
it either bin/marble or bin/marble-kde
- Have cmake options (like BUILD_MARBLE_DESKTOP_QT,
BUILD_MARBLE_DESKTOP_KDE) for those who don't like the defaults / auto
detection

Keeping the KDE version as bin/marble (instead of bin/marble-kde) would
be less confusing for those used to executing the binary directly
(instead of using a .desktop file) at the cost of losing some
consistency, but probably worth doing.

Please speak up if you don't want that change / see major disadvantages.
Otherwise I'd work on it for 1.6 (after the current freeze).

Regards,
Dennis