Beginning of Directory.Build.props settings

Can create that file in the root with:

```
<Project>
  <PropertyGroup>
    <KspDir>/Users/lamont/ksp/plc_1.12.3</KspDir>
  </PropertyGroup>
</Project>
```

And it'll get passed into copy_build.sh

Or KSPDIR will override that setting

Signed-off-by: Lamont Granquist <lamont@scriptkiddie.org>

MechJeb2/MechJeb2.csproj

@@ -265,7 +265,7 @@
         <Exec Command="call &quot;$(ProjectDir)copy_build.bat&quot; &quot;$(TargetPath)&quot; &quot;$(TargetDir)&quot; &quot;$(TargetName)&quot; &quot;$(ProjectDir)&quot;"/>
     </Target>
     <Target Name="AfterBuild" Condition=" '$(OS)' != 'Windows_NT' ">
-        <Exec Command="'$(ProjectDir)/copy_build.sh' '$(TargetPath)' '$(TargetDir)' '$(TargetName)' '$(ProjectDir)' '$(ReferencePath)'"/>
+        <Exec Command="'$(ProjectDir)/copy_build.sh' '$(TargetPath)' '$(TargetDir)' '$(TargetName)' '$(ProjectDir)' '$(KspDir)'"/>
     </Target>
     <!-- To modify your build process, add your task inside one of the targets below and uncomment it.
          Other similar extension points exist, see Microsoft.Common.targets.

MechJeb2/copy_build.sh

@@ -3,7 +3,7 @@ TARGET_PATH=$1
 TARGET_DIR=$2
 TARGET_NAME=$3
 PROJECT_DIR=$4
-REFERENCE_PATH=$5
+KSPDIR=$5
 
 if [ -z "${TARGET_PATH}" ] ; then
   echo 'Expected $TARGET_PATH to be defined but it is not' >&2
@@ -31,15 +31,6 @@ if [ -z "${PROJECT_DIR}" ] ; then
   exit 1
 fi
 
-if [ -z "${REFERENCE_PATH}" ] ; then
-  echo 'Expected REFERENCE_PATH to be defined but it is not' >&2
-  exit 1
-fi
-
-if [[ $(uname -s) = Darwin ]]; then
-  KSPDIR="$(dirname "$(dirname "$(dirname "$(dirname "$(dirname "$REFERENCE_PATH")")")")")"
-fi
-
 if [ -z "${KSPDIR}" ] ; then
   if [[ $(uname -s) = Linux ]]; then
     KSPDIR="${HOME}/.local/share/Steam/SteamApps/common/Kerbal Space Program"