ZedGraph 5.2.1

ZedGraph 5.2

* Rename ZedGraph.csproj to ZedGraph.Net35.csproj
* Moved a few code files from source to source/ZedGraph
* Add ZedGraph.csproj
* Update ZedGraph.csproj.nuspec
* Bump ZedGraph.Net35 project to 5.2.0
* Fix EmbeddedResource compilation
* Update revision history

Add logo

Add nuget links to readme

Update version information

Update nuget package spec.