Drop unused Microsoft.Bcl.HashCode, fix README typo

HashCode.Combine is called nowhere; the package (and its DLL in the dist
zip) was dead weight since the Core projects were created.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

README.md

@@ -96,7 +96,7 @@ The two apps need a crossed serial link. Install a
 (e.g. `COM1 ⇄ COM11`), then:
 
 1. Run `VRio.App`, pick `COM11`, **Open**.
-2. RIOJoy will always poit to `COM1`.
+2. RIOJoy will always point to `COM1`.
 
 RIOJoy's DTR open-pulse shows up in the wire log (DSR handshake), its ~55 ms
 analog polling drives the "analog polls served" counter, and every click on

src/VPlasma.Core/VPlasma.Core.csproj

@@ -12,7 +12,6 @@
 
   <ItemGroup>
     <PackageReference Include="System.Memory" Version="4.5.5" />
-    <PackageReference Include="Microsoft.Bcl.HashCode" Version="1.1.1" />
     <PackageReference Include="PolySharp" Version="1.14.1">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>

src/VRio.Core/VRio.Core.csproj

@@ -12,7 +12,6 @@
 
   <ItemGroup>
     <PackageReference Include="System.Memory" Version="4.5.5" />
-    <PackageReference Include="Microsoft.Bcl.HashCode" Version="1.1.1" />
     <PackageReference Include="PolySharp" Version="1.14.1">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>