[CL/Exit] Add Sleep menu item and option to come back to the other CL menus

[Aneemasta]

New Feature

1. Exit menu has items Restart and Shutdown, but no Sleep mode. I know that sleep mode can be enabled from anywhere via power button, but still it probably would be logical to have Sleep item there.
2. Currently when you open Exit menu from the CL menu switch (pressing triangle), the only option to go back to the rest of CL menus is either to Exit to the XMB and launch CL again or to Restart PSP and launch CL again. Pressing triangle there does nothing. Could you please add same triangle-press call of menu switch there or maybe Back to games menu item?