message: Add v1.12.0-beta3 items to the changelog
diff: * Update debugger to run *itself* on .NET Core 2.0-preview2 (target app can still use .NET Core 1.x). This allows the debugger to run on more Linux distributions, and it allows there to be a single debugger package for all supported Linux distributions.
  * Fix issue where the call stack may be empty when stepping quickly ([#1575](https://github.com/OmniSharp/omnisharp-vscode/issues/1575))
  +* Improvements to the information displayed in the editor peak window when stopping on an exception that has inner exceptions ([#1007](https://github.com/OmniSharp/omnisharp-vscode/issues/1007))
  +* Fix expression evaluation when stopping at an exception in .NET Core 2.0 ([#1593](https://github.com/OmniSharp/omnisharp-vscode/issues/1593))
  +* Improve error behavior when `"program"` in launch.json is set to a path that doesn't exist ([#1634](https://github.com/OmniSharp/omnisharp-vscode/issues/1634))
  +* Enable stepping by statement (instead of by line) ([#1476](https://github.com/OmniSharp/omnisharp-vscode/issues/1476))
  #### Editor
  #### Other Updates and Fixes
  +* Switched to a new CDN for the extension's dependencies which should deliver an improved download experience ([#1542](https://github.com/OmniSharp/omnisharp-vscode/issues/1542))
  * Automatically activate the extension when opening workspaces that contain any .csproj, .sln, or .csx files ([#1375](https://github.com/OmniSharp/omnisharp-vscode/issues/1375), [#1150](https://github.com/OmniSharp/omnisharp-vscode/issues/1150), PR: [#1592](https://github.com/OmniSharp/omnisharp-vscode/pull/1592)))
  * All project systems (project.json, MSBuild, CSX Scripting) now support an "Enabled" property that can be configured in omnisharp.json. (PR: [omnisharp-roslyn#902](https://github.com/OmniSharp/omnisharp-roslyn/pull/902)) _(Contributed by [@filipw](https://github.com/filipw))_
  * The OmniSharp server has been updated to Roslyn 2.3.0-beta2, which adds support for C# 7.1 (PRs: [omnisharp-roslyn#900](https://github.com/OmniSharp/omnisharp-roslyn/pull/900) and [omnisharp-roslyn#901](https://github.com/OmniSharp/omnisharp-roslyn/pull/901))
  