Opening the PR for visibility and potential discussions.
This PR upgrade old Roslyn CTP from September 2012 to version 1.0.0 RC2 (.NET 4.5 compatible). Also includes a VB engine. The core work was done in this repo already https://github.com/scriptcs/scriptcs-engines

Version 1.1.0-beta is .NET 4.6 only so we will have to discuss separately what to do about it.

TODO

• fix/troubleshoot the 8 failing tests
• internalize the Roslyn DLLs into a lib folder (currently referenced from NuGet as pre packages)
• ensure the new engines actually run (they used to work as external modules, but now due to changes around ILog, they don't)
• fix build.cmd (note: acceptance tests still fail)
• fix nuget package creation (*note: see questions below, we now have new nuget packages: scriptcs.csharp and scriptcs.visualbasic)
• fix acceptance tests
• check build on OS X (old solution used to build there)
• fix Travis CI (although the issue on Travis existed before see https://travis-ci.org/scriptcs/scriptcs/builds/68478618
• smoke tests etc etc

Questions & issues

• What do we do about naming? In the engines repo we called it ScriptCs.CSharp, should we keep this name or stick with ScriptCs.Engine.Roslyn? Right now I renamed everything to csharp and visualbasic respectively, so roslyn is no longer visible anywhere
• This bug [scriptcs] handling importing of invalid namespaces in the REPL dotnet/roslyn#1012 forced me to comment out 2 tests, and we no longer can determine if an invalid namespace has been added. It is a regression compared to old Roslyn engine.
• How do we determine that this should be merged? I would like to establish some process that will allow us to get this moving, there is no point in waiting and waiting

Next steps

Update to Roslyn 1.1.0-beta? However, as mentioned, that's .NET 4.6 only.