Output ground files as executable

src/main.cpp

@@ -1,4 +1,5 @@
 #include <cstdio>
+#include <cstdlib>
 #include <groundvm.h>
 #include <string>
 #include <fstream>
@@ -56,8 +57,9 @@ int main(int argc, char** argv) {
             if (!outputFile) {
                 std::cout << "Failed to write to " << args.output.value().value << "\n";
             }
-            outputFile << result;
+            outputFile << "#!/usr/bin/env ground\n" << result;
             outputFile.close();
+            system(std::string("chmod +x " + args.output.value().value).c_str());
             exit(0);
         } else if (args.outputtype.value().value == "native") {
             std::string assembly(groundCompileProgram(&program));