qdoc: Support use of \value command outside \enum topic.

Even though qdoc accepts the \value command(s) anywhere in the
documentation and generates tables for them, the produced output was
invalid for documentation topics other than \enum.

This change fixes the issue by not trying to resolve the enumeration
values and removing the 'Value' column for generated tables when the
\value command is used outside c++ enum documentation topic.

This enables, for example, the use of the \value command for
documenting acceptable values for QML enumeration properties,
without having to use custom lists or tables.

Task-number: QTBUG-35019
Change-Id: I597b2f9d7d03d4ab72f276752ddf53e1c405313c
Reviewed-by: Jerome Pasion <jerome.pasion@digia.com>
Reviewed-by: Martin Smith <martin.smith@digia.com>
qdoc: Validate index file paths

Check for existence of the paths added by 'indexes'
documentation configuration command, and generate
warnings accordingly. Also, ensure that the strings
added with 'depends' command contain no duplicates.

Change-Id: I66a3d1b25907567bb5bfc72b78a8009d7bd8e067
Reviewed-by: Martin Smith <martin.smith@digia.com>
Reviewed-by: Jerome Pasion <jerome.pasion@digia.com>
Implement QApplication::topLevelAt() using QGuiApplication::topLevelAt().

Reducing code duplication, preparing for High-DPI support.

Task-number: QTBUG-38858
Change-Id: Id0ed12db4b5cadd0eef79afd0ac62f58a7b01901
Reviewed-by: Jørgen Lind <jorgen.lind@digia.com>
Fix up existing high DPI manual test.

Compile on Windows, add command line options to activate the
various tests.

Task-number: QTBUG-38858
Change-Id: I38c6a9a6711831b2bd8b6ea051dd19615cc911a1
Reviewed-by: Alessandro Portale <alessandro.portale@digia.com>
QRingBuffer: purge unused part of the api

Remove unused and untested class functions.

Change-Id: I8eb963db0ae4be9b5cdde91f6747c4a1db4ea649
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>