- added (base) test cases for the lexer issues and 2 test files. The d="" luckily seems to 
  behave as expected (did crash in earlier versions)
- found the exact line in the CSS that failed (border with !important) and isolated the test
- updated names of the tests and files
- added a reference test for the non important line (which should always work).
- fixed small spelling error in the css parser.
- added trailing whitespace test for #399, which also crashes the lexer 

- fixes #331

Updated threading tests to use the resource file, updated the file loader in the test helper to be flagged as obsolete and changed the working of the multi-threading fail test since this is not always failing with the error while processing the SVG. If it's not failing now it will be flagged inconclusive.

Added a test with a SvgText element where the whole text element was not written to XML of a deep copy of the SvgDocument.

- Changed SvgImage.Href property from Uri type to String to avoid UriFormatException if Uri contains too much data
- Changed GetImage to receive a string instead of Uri object.
  - Created a temp Uri object in method with substring of allowed length and using this to determine Uri characteristics

As long as the functions AdjustForViewBoxWidth and
AdjustForViewBoxHeight are not fully developed pay attention that the
ViewBox width and height will not mismatch the positions of the marker
element then one of them are zero.

This changes are based on Issue #212 from mater.

Add: Quick solution to avoid  ViewBox width or height zero calculation.
Add: UnitTests

Create metafile rendering Unit Test based on Issue #210 from master.

This reverts commit a7097113.

This reverts commit 480a54d8.

Based on Issue #204.
Now users can add customer fonts/ private fonts to
SvgElement.PrivateFonts.

Unit Test:
Add Test: PrivateFontsTest
Add Resources from PrivateFontsTest.
Add SvgTestHelper
Change MultiThreadingTest, now based on SvgTestHelper to use shared code
(no code duplication)

Note:
MuliThreadingTest TestFile is not available. The vvvv/master should add
the test file to the resources or other developer can not test the svg
engine.