* Remove sources that have now migrated to the central AspNetCore repo
* Move remaining blazor/src to src
* Update readme; rename .sln file
* Clean up .sln file
* Remove unnecessary files. Simplify build config.
* Ensure correct build order
Changed CODE_OF_CONDUCT link to relative (absolute link was dead) and changed target branch for aspnet in "Contributing code and content" section to master since the dev branch no longer exist.