Store fix in place

I have fixed a few errors with the store. One error would occasionally sell people an item other than the one they were trying to buy... when dealing with expensive items, this was a very annoying glitch. Another error allowed items sold by a player to get added to the wrong store item's inventory, sometimes creating 'illegal' items in the store inventory, i.e. unaligned hard items that are supposed to carry alignment, etc.. A related error could create negative quantities of items in the store inventory upon purchase from the store.

Some of these glitches above, while rare, could cause the game to crash on occasion.

Significant patches to the store code have been made to prevent the above errors. As part of this patch, you may see some messages from the store that you haven't seen before.. i.e. if you are trying to purchase an item, and someone else buys the last one out of the store's inventory, the store will tell you what happened, pause and back you out to the main 'buy an item' page.

In addition, some small changes to the store display and navigation code were made that should make it easier to purchase an item while you are looking at its features.

I've tested this code pretty thoroughly, and I have not been able to repeat the aforementioned errors. This fix is now running on the live server. Please let me know if any store anomalies persist.