Fully expand entities to ensure deep or widely nested ones fail parsing

With 46a8885ae486e238a39efa5119c2714f328b08e4, we failed when parsing
entities whose partially expanded size was greater than 1024
characters. That was not enough, so now we fully expand all entities.

Amends 46a8885ae486e238a39efa5119c2714f328b08e4.

Change-Id: Ie80720d7e04d825eb4eebf528140eb94806c02b1
Reviewed-by: Richard J. Moore <rich@kde.org>
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
Check for existence of QML import paths.

Filter out module QML import paths that point to 
nonexistent file system paths.

Change-Id: I897ef50593eeb46c6c9eaec27313ec12e6113cb6
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@digia.com>