Use of MSBuild properties (by default) in Addon/Game/Code Library .csproj files.

[MillzyDev]

I usually like to make my code easy to pickup development on other devices, for the sake of myself and other developers. With this is mind, I think it would be a good idea if instead of using absolute paths for resolving references and items from the s&box installation directory (by default), we could use an MSBuild property, such as SolutionDir for example to make it "more relative".

<ItemGroup>
        <Analyzer Include="D:\Steam\steamapps\common\sbox\bin\managed\Sandbox.Generator.dll"/>
        <Reference Include="D:\Steam\steamapps\common\sbox\bin\managed/Sandbox.System.dll" />
        <Reference Include="D:\Steam\steamapps\common\sbox\bin\managed/Sandbox.Engine.dll" />
        <Reference Include="D:\Steam\steamapps\common\sbox\bin\managed/Sandbox.Game.dll" />
        <Reference Include="D:\Steam\steamapps\common\sbox\bin\managed/Sandbox.Event.dll" />
        <Reference Include="D:\Steam\steamapps\common\sbox\bin\managed/Sandbox.Bind.dll" />
        <Reference Include="D:\Steam\steamapps\common\sbox\bin\managed/Sandbox.Reflection.dll" />
</ItemGroup>

<ItemGroup>
        <Analyzer Include="$(SolutionDir)\bin\managed\Sandbox.Generator.dll"/>
        <Reference Include="$(SolutionDir)\bin\managed/Sandbox.System.dll" />
        <Reference Include="$(SolutionDir)\bin\managed/Sandbox.Engine.dll" />
        <Reference Include="$(SolutionDir)\bin\managed/Sandbox.Game.dll" />
        <Reference Include="$(SolutionDir)\bin\managed/Sandbox.Event.dll" />
        <Reference Include="$(SolutionDir)\bin\managed/Sandbox.Bind.dll" />
        <Reference Include="$(SolutionDir)\bin\managed/Sandbox.Reflection.dll" />
</ItemGroup>

Very minor thing, seeing as you can easily change this anyway by doing Ctrl + H (in Rider/for me) to replace all occurances. I just feel it would be a better thing to have by default. Can't hurt to just throw the idea out there.