* Snap of sln reader/writer from https://github.com/mono/monodevelop
* Remove unnecessary code
* Create a new test asset with an sln file because adding an sln to an existing one broke other tests
* Remove commented out line
* Removing unneeded PropertyGroup per PR comments
* Update the license
* Fixing the license
This adds LZMA to the THIRD-PARTY-NOTICES list for CLI. Since we've
modified the SDK in porting it to .NET Core and minor bugfixes we've
also been advised to add the .NET Foundation copyright header.