widget/graphicsview: Do not run tests showing windows in parallel.

Change-Id: I3bba3f49eba6ca9c187caf696d0f6c73372fec5d
Reviewed-by: Andreas Aardal Hanssen <andreas@hanssen.name>
Make QTime::toString output milliseconds for Qt::TextDate, Qt::ISODate.

Section 4.2.2.4 of ISO 8601 allows for decimal fraction representations
of dates and times. Currently, when calling
QDateTime::toString(Qt::TextDate) or QDateTime::toString(Qt::ISODate),
the milliseconds will be omitted. However,
QDateTime::fromString(str, Qt::TextDate) and
QDateTime::fromString(str, Qt::ISODate) already support decimal
fraction representations, so this patch just adds this support to
QTime::toString, and hence QDateTime::toString().

Task-number: QTBUG-30250
Change-Id: If58e4b3d3105322c51d11a76b832e5e634d8991f
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
QNetworkAccessManager: add public methods to pre-TCP/pre-SSL-connect

If an app knows it needs to connect to a host beforehand, it can "warm up" the
connection cache by making DNS lookup, TCP (and if needed SSL) handshake before
the actual HTTP request is sent. When the HTTP request is made, it will be
considerably faster when there is already a working connection.

Here are some typical results from the benchmark:

* Linux desktop with Ethernet:
  "http://www.google.com" full request: 279 ms, pre-connect request: 61 ms,
    difference: 218 ms
  "https://www.google.com" full request: 344 ms, pre-connect request: 60 ms,
    difference: 284 ms

* mobile device (BlackBerry 10) with Wifi:
  "https://www.google.com" full request: 898 ms, pre-connect request: 159 ms,
    difference: 739 ms
  "http://www.google.com" full request: 707 ms, pre-connect request: 200 ms,
    difference: 507 ms

Task-number: QTBUG-30771
Change-Id: I3566b7f08216ab93a39e2024ae7d1ceb7ae21891
Reviewed-by: Jonas Gastal <gastal@intel.com>
Reviewed-by: Richard J. Moore <rich@kde.org>