Warn against access to uninitialized project data.

Change-Id: I904db460da1874b29a0d674b2e3b9d7e548c6da5
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
Name all the Qt module files consistently.

The majority of the files do not have the 'qt' prefix, so sync 'em up.

Change-Id: Ifb4eb46f2c9af50c6db9da7704ec54b9d47cbaa4
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
Prepare qbs project files for selective inclusion.

Namely:
- Move product "share" into its own file.
- Move version number definition into its own file.

This will make it easier to pull in only parts of the sources
in an aggregating project (e.g. an IDE that does not need the executables).

Change-Id: I41b724fe8a0b20d957b924fe0a827263add43dce
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>