- 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 

- 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

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.

Unit Test Expected Size correction with same buffer like in Unit Test
MultiThreadingTest.

Add image comparer.

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.