Use 48x48 block size

[cxong]

To improve visibility, the block size for half gfx is enlarged to 24x24. To keep things consistent, the normal size is also changed to 48x48.

This causes two issues for the normal game mode:

• The grid no longer fills the screen; the "top" is below the top of the screen so it's not clear when players will lose
• The status bar, which previously covered the lowest row, no longer does so, both due to the non-matching grid size and larger blocks. This means that as the rows are rising, there's a period where an empty gap exists between the status bar and the first block row.

How do you want to solve these two issues? The first one can be helped by adding a border to the background like the jewels background; the second one by adding an extra row and adding a draw Y offset to the entire grid so there is never any gap at the bottom.

[dorkster]

This (and the needed fixes you mentioned) are exactly what I had in mind. I'll work on fixing the background and the gap today and get this merged in.