Do not list library symlinks as input to linker rule.

There is no reason for that.

Change-Id: I76e280c38340a4e5bd528c16b3810605ad88d74f
Reviewed-by: Jake Petroules <jake.petroules@petroules.com>
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
Allow directories in "references" properties.

Such a construct will work if the given directory contains exactly
one project file, identified by the ".qbs" extension.
This saves annoying redundancies of the form
"references: 'mysubproject/mysubproject.qbs'".

Change-Id: Ief0f52f788189b7fb2e4764b692159b570fe444c
Task-number: QBS-454
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
trace include paths used in scanner

Change-Id: I3e3e0c6aeba58489ad37017ecf61e636ba17e892
Reviewed-by: Christian Kandeler <christian.kandeler@digia.com>