ENH: Initial changes to replace findQt4 with Qt5 libraries

Exclusively build against Qt5
Change-Id: Ie6fa3cef970992f42ef33833a5c87735e18813a5
Set VTK_QT_VERSION

Change-Id: If5c6bf8e752d4b410873c8715f0f64dca79fe783
Changed all qt4 macros to qt5

Change-Id: I597baeeca4bb64f17e4a3682715aca1983f1473e
Compile flags (-fPIE) for position independent code

Qt5 is built and packaged with the -reduce-relocations configure option as
default. This causes compilations to run with the -Bsymbolic-functions option,
which makes function pointer comparison ineffective, unless the -fPIE flag is
also supplied.

Change-Id: I61d13993e0cc6fee2e38e8a124e32459f6203d40
Qt5 obsoletes toAscii and fromAscii methods

Replaced all instances:
QString::toAscii --> QString::toLatin1
QString::fromAscii --> QString::fromLatin1
QChar::fromAscii --> QLatin1Char

Change-Id: Ic4f9c5316c73a305ded835e02fc3ff6babffdf39
Obsoleted methods from QHeaderView

Replaced all instances:
QHeaderView::setClickable --> QHeaderView::setSectionsClickable
QHeaderView::setResizeMode --> QHeaderView::setSectionResizeMode
QHeaderView::setMovable --> QHeaderView::setSectionsMovable

Change-Id: I6e583e322db1ebc902d6c86da284f4eef6e36dce
Qt5 obsoletes global typedef qInstallMsgHandler and QtMsgHandler

Using qInstallMessageHander and QtMessageHandler
QtMessageHandler has a different signature than QtMsgHandler providing
information about context. Incorporated that information in the vtkOutputWindow
message printout.

Change-Id: I2c0b9fac88ee2dd28b08d1108654b1983fb7b0fe
QAbstractItemModel::reset() and QAbstractItemModel::createIndex

QAbstractItemModel::reset -
The deprecated function emitted two signals, namely modelAboutToBeReset and
modelReset. Using beginResetModel and endResetModel to emit these signals
instead.

QAbstractItemModel::createIndex -
Ambiguity when compiling with gcc.
When the last parameter is either NULL or 0, GCC fails to resolve
which path to follow. Use the default value (void* ptr = 0) provided in the
function declaration.

Change-Id: I6df26e314bbff6522dab8cd48d328b8b065d91b8
Qt5 related changes

1. QCursor constructor needs QPixmap instead of const char*
2. Qt::WFlags obsoleted. Replaced by Qt::WindowFlags
3. QPixmap::serialNumber() deprecated. Replaced by QPixmap::cacheKey()
4. QVariant(Qt::GlobalColor) is now private. Use QVariant(QColor(Qt::GlobalColor)) instead.
5. QMetaMethod::signature obsoleted. Replaced by QMetaMethod::methodSignature().
6. QDir::convertSeparators obsoleted. Replaced by
   toNativeSeparators/fromNativeSeparators
7. QRegion::unite deprecated. Replaced by QRegion::united
8. QCoreApplication::UnicodeUTF8 is deprecated.
9. Missing includes

Change-Id: I44861d866aa2b2b5cb339b620c120a0c075ffd55
Obsoleted constructor for QGraphicsItem

Removed the use of QGraphicsScene from the constructor argument.

Change-Id: I696417dc65db7b978ab35ae07a8f4d4e5b18c640
QtGui library -> include QtGui/* files directly

Change-Id: If348023b9caec26b63c69e257516fb89d494ec08
QWindowsStyle and QPlastiqueStyle obsoleted

Replaced with the Fusion style and the new QStyleFactory::create() API.

Change-Id: Icc89344182f76c07af93600308afac7762ff52ed