Fairly hefty re-write

Re-wrote many parts of SwitchGameManager!

Moved SD games to their own list.
Added ability to switch between PC and SD.
Added SD file size on the main form.
Check SD available space before transferring games.
Re-worked file transfers.
Improved performance by loading games in a background worker (much more responsive UI)
Improved menus to show game/game count selections.
Added monitoring for SD inserted/removed.
Fix issue with SD card not being in Ready state.
Added option to open to file location in Windows Explorer.