Add settings::isPlugin.

include/settings.hpp

@@ -25,6 +25,7 @@ namespace settings {
 extern std::string settingsPath;
 extern bool devMode;
 extern bool headless;
+extern bool isPlugin;
 
 // Persistent state, serialized to settings.json.
 

src/settings.cpp

@@ -18,6 +18,7 @@ namespace settings {
 std::string settingsPath;
 bool devMode = false;
 bool headless = false;
+bool isPlugin = false;
 
 std::string token;
 bool windowMaximized = false;