古いSDLでも動くようにした

dub.json

@@ -1,7 +1,7 @@
 {
 	"name": "otyasmilebasic",
 	"dependencies": {
-		"derelict-sdl2": "*",
+		"derelict-sdl2": "~>1.9.7",
 		"derelict-gl3": "*"
 	},
 	"sourceFiles": ["SMILEBASIC/bg.d","SMILEBASIC/builtinfunctions.d","SMILEBASIC/compiler.d","SMILEBASIC/error.d","SMILEBASIC/main.d","SMILEBASIC/node.d","SMILEBASIC/parser.d","SMILEBASIC/petitcomputer.d","SMILEBASIC/sprite.d","SMILEBASIC/systemvariable.d","SMILEBASIC/token.d","SMILEBASIC/type.d","SMILEBASIC/VM.d","SMILEBASIC/project.d"],
@@ -10,4 +10,4 @@
 	"targetPath": "out",
 	"workingDirectory": "out",
 	"copyFiles": ["SMILEBASIC/spdef.csv"]
-}
+}