fix confusion surrounding debug, release & debug_and_release

Done-with: Leena Miettinen <riitta-leena.miettinen@digia.com>
Change-Id: I1e031402bc3d857cf29782957e5340e3c82f1ed2
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@digia.com>
make qmake auto-rebuild after path reconfiguration

while the dependencies in the manual projects are crappy anyway, it is
still worth to cover the case of the user changing the install paths.

Change-Id: I0a7ca5c8ba660c689d6d7af6b65d878390d6456f
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
clean out some garbage in CONFIG

- thread was duplicated
- x86 & ppc are obsolete and don't actually do anything
- incremental was just plain nonsense (it does something entirely
  different, and it's better to hide this "feature" from public view)
- resources is basically an implementation detail (it's on by default if
  qtcore is used)

Change-Id: I9163af6e8db7988382ccf993d4be280f7faec1f2
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@digia.com>
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>