- fixes #323 (caused crash)

- set correct default for fill/stroke unset color
- fixes #398

- fixes #191

- added test image for new issue
- all passing W3C images shall now correctly be shown in passing tab

the recently introduced optional size parameter is causing incompatibilities with our C++ application.

Unit Calculation: add spaces between operatores, remove obsolete default branch in switch statement.
bug fix #338

Fix issue with percentage unit in "stroke-width", now taken from the viewbox width/height normalised diagonale for x/y elements e.g. circle
Test images and svg under #338

- fixes #58

- could break the functionality if writing is not possible in root
- see #372

Fix Issue #385, using TextBounds.Width rather than path bounds to ensure proper font alignment for "middle" and "end" - see also "text-align-03-b"

- added "stroke-dashoffset" support
- added "painting-stroke-04-t" to "PassingTests" (csv/txt)
- fixes #388 

- see #384

- added a few of them to passing image comparson tests

- added image broken by regression to tests (__Flag_of_the_United_States)
- added some passing issue specific tests to image comparison tests

- first try for a matching comparison test
- compares down-scaled gray-scale images pixel-wise
- see #378

See ExCSS pull request #62: https://github.com/TylerBrinks/ExCSS/pull/62

- found by @Seairth
- fixes #108

- ignore elements with recursive references
- fixes stack overflow for test image struct-use-12-f.svg

- Catch exceptions in event handler.

- originally provided by @ssteiger in #316

- fixes TestPrivateFront unit test (threw exception because the image
  had zero size, as the only element is a "use" element)

- vertical graphics context resolution has been used incosistently which leads to wrongly positioned texts when printing

- ignore textLength attribute if X attribute is list
- add test images

- fixed a few other tests by using the Svg DTD Resolver to avoid web requests

- suppress warning CS1591: Missing XML comment for publicly visible type or member
  to avoid to overflow the build log with warnings
- fixed the rest of the documentation warnings in SVG project
- ignore all failing tests for the time being

- Fix: adjustment is wrong in lengthAdjust='spacingAndGlyphs'.
- Add test images.

fixed SvgAttrribute reflection for .net core. (i guess Equals() function is called instead of Match() on this platform?)

In <image> element, preserveAspectRatio attribute default value is 'xMidYMid meet'.

https://www.w3.org/TR/SVG11/coords.html#PreserveAspectRatioAttribute

# image opacity fix