control moved into gemma for launch/stop/step of cpu core

gemma/src/chip8/system_memory.rs

@@ -44,7 +44,7 @@ impl Chip8SystemMemory {
         }
     }
 
-    pub fn peek(self, address: u16) -> u8 {
+    pub fn peek(&self, address: u16) -> u8 {
         trace!("PEEK: {} / {}", address, self.memory[address as usize].clone());
         self.memory[address as usize]
     }