Icons for Qt Creator.

In various eras, we collected images/icons in .png format
from different sources. In some cases from hired designers,
some contributors, and even some Qt Creator developers.
That causes more or less subtle in consistencies ranging
from color schemes to shadow directions.

Now - in the era of High-Dpi - we suddenly need high
resolution "@2x" versions of our graphics, but do not have
the original graphics files to easily generate them.

This approach here supplies many of the graphics in SVG,
editable with Inkscape. Existing pngs are re-created as
vector graphic. That way, the original graphics
sources are finally public and version controlled. Also,
we potentially get more consistent graphics and
High-resolution versions.

The shell script executes Inkscape to export the images and
icons as pngs.

Change-Id: Id426ee94b151833cd52e29a8234966aba9cd38bc
Reviewed-by: Orgad Shaneh <orgads@gmail.com>
Reviewed-by: Adam Strzelecki <ono@java.pl>
Reviewed-by: Alessandro Portale <alessandro.portale@digia.com>