Disable "prefer 32 bit" build flag

The build flag causes the application to run as a 32-bit app on 64-bit
systems, which we don't want.  We're still using "Any CPU" as the
platform target, so it will continue to work on 32-bit x86 systems;
we just no longer force it to always be 32-bit.

This only affects the main .NET Framework application executable.
The setting is not relevant for the libraries.

(Note to future self: the way things work changed with .NET Core,
which requires different executables for different targets, specified
with the RID.  The older .NET Framework is Windows-only, which makes
it easier to have a single multi-target EXE.)

SourceGen/SourceGen.csproj

@@ -24,6 +24,7 @@
     <DefineConstants>DEBUG;TRACE</DefineConstants>
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>
+    <Prefer32Bit>false</Prefer32Bit>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
     <PlatformTarget>AnyCPU</PlatformTarget>
@@ -33,6 +34,7 @@
     <DefineConstants>TRACE</DefineConstants>
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>
+    <Prefer32Bit>false</Prefer32Bit>
   </PropertyGroup>
   <PropertyGroup>
     <ApplicationIcon>Res\SourceGenIcon.ico</ApplicationIcon>