Call fgInitAllowedPaths() earlier: after Options::processOptions()

Call fgInitAllowedPaths() right after Options::processOptions() (which,
among other things, determines $FG_ROOT and processes
--allow-nasal-read). This way, fgInitAllowedPaths() can be used in much
more code, such as when initializing subsystems.

src/Main/fg_init.cxx

@@ -1145,6 +1145,11 @@ void fgStartNewReset()
     
     flightgear::Options::sharedInstance()->processOptions();
 
+    // Rebuild the lists of allowed paths for cases where a path comes from an
+    // untrusted source, such as the global property tree (this uses $FG_HOME
+    // and other paths set by Options::processOptions()).
+    fgInitAllowedPaths();
+
     const auto& resMgr = simgear::EmbeddedResourceManager::instance();
     // The language was (re)set in processOptions()
     const string locale = globals->get_locale()->getPreferredLanguage();

src/Main/main.cxx

@@ -541,6 +541,11 @@ int fgMainInit( int argc, char **argv )
         return EXIT_SUCCESS;
     }
 
+    // Set the lists of allowed paths for cases where a path comes from an
+    // untrusted source, such as the global property tree (this uses $FG_HOME
+    // and other paths set by Options::processOptions()).
+    fgInitAllowedPaths();
+
     const auto& resMgr = simgear::EmbeddedResourceManager::createInstance();
     initFlightGearEmbeddedResources();
     // The language was set in processOptions()

src/Scripting/NasalSys.cxx

@@ -911,10 +911,6 @@ void FGNasalSys::init()
       .member("simulatedTime", &TimerObj::isSimTime, &f_timerObj_setSimTime)
       .member("isRunning", &TimerObj::isRunning);
 
-
-    // Set allowed paths for Nasal I/O
-    fgInitAllowedPaths();
-
     // Now load the various source files in the Nasal directory
     simgear::Dir nasalDir(SGPath(globals->get_fg_root(), "Nasal"));
     loadScriptDirectory(nasalDir);