Doc: Update Qt licensing documentation

Add information about the license for WebP (libwebp) version 0.4.0 which
is in Qt Image Formats module.

Task-number: QTBUG-42710
Change-Id: Ia0047c59d162081b901420979240bef2c0cda962
Reviewed-by: Sami Makkonen <sami.makkonen@digia.com>
Reviewed-by: Martin Smith <martin.smith@digia.com>
Update ANGLE section in 3rdparty licenses

Change-Id: Iacfd74e399bb93d7d64fbc08ff458546d4b0f34f
Reviewed-by: Andrew Knight <andrew.knight@theqtcompany.com>
Update sqlite version  in 3rdparty licenses

Change-Id: Ied6ae240fa8660f5914abfa17c0920ea7a9365ed
Reviewed-by: Maurice Kalinowski <maurice.kalinowski@theqtcompany.com>
Doc: Changed layout to use the empty spaces efficiently

- Added images and text within \raw HTML tables to remove
  the default background and size restrictions.
- Replaced the controls gallery example screenshots with
  the latest ones.
- Added a screenshot of the Qt WebEngine nano browser example
- Fixed a few typos

Change-Id: Ie0d03916db98ef0ad88e6f92e51177a5a8260c9a
Reviewed-by: Topi Reiniö <topi.reinio@digia.com>
Doc: Update licensing documentation

Add information about the following licenses:
   - libjasper version 2.0 (qtimageformats)
   - Mesa llvmpipe software rasterizer

Also, remove the use of '\generatelist legalese' command
from the licensing docs, as it results in duplicate entries.

Task-number: QTBUG-42173
Task-number: QTBUG-42711
Change-Id: Ie8a60e01a597fa4c28adf251e8fecd222d3de468
Reviewed-by: Sami Makkonen <sami.makkonen@digia.com>
Reviewed-by: Martin Smith <martin.smith@digia.com>
Merge remote-tracking branch 'origin/5.4.0' into 5.4

Change-Id: I10a73c7f3011e8d9ee40d9b19be3a7d463515bda