[WIP] Overhauled project to make Linux build work out of the box

TODO: fix the Windows build, fix the Debug builds, make OSX
configurations, work around a bug in MonoDevelop where copied content
files don't respect the original directory structure

Libraries/Farseer Physics Engine 3.5/Farseer Physics.csproj

@@ -40,6 +40,7 @@
     <UseApplicationTrust>false</UseApplicationTrust>
     <BootstrapperEnabled>true</BootstrapperEnabled>
     <TargetFrameworkProfile />
+    <ReleaseVersion>0.7.0.1</ReleaseVersion>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
     <DebugSymbols>true</DebugSymbols>
@@ -67,7 +68,6 @@
   <ItemGroup>
     <Reference Include="System" />
     <Reference Include="System.Core">
-      <RequiredTargetFramework>3.5</RequiredTargetFramework>
     </Reference>
     <Reference Include="System.Xml" />
   </ItemGroup>