Restore ProjectK package once.

build/_k-standard-goals.shade

@@ -12,6 +12,7 @@ default TEST_DIR='${Path.Combine(TARGET_DIR, "test")}'
 }
 
 #target-default target='default'
+  nuget-install package='ProjectK' outputDir='packages' extra='-pre'
   k-restore
   k-generate-projects solutionPath='${BASE_DIR}'
 

build/_k.shade

@@ -12,7 +12,7 @@ kProgram='...'
 command=''
 
 */}
-nuget-install package='ProjectK' outputDir='packages' extra='-pre' 
+
 @{
     string packagesDir = Path.Combine(Directory.GetCurrentDirectory(), "packages"),
            projectKDir = Directory.EnumerateDirectories(packagesDir, "ProjectK*")