scroll changing bts
using the unused block type and bts values, changes neighboring scrolls

high nibble should be a value to change the scroll to
low nibble should be a value between 0-8, which is direction
see screenshot image for visual clarification

for example, a bts of 01 will change the scroll above you to a red scroll, and a value of 16 will change the scroll below and to the left of you to a blue scroll
00 is highly unlikely to be used, but would change the current scroll you are in to red

edit: amoeba convinced me to modified the code slightly, now supports any value between 0 and F as a valid scroll value to change into, and modified index to allow for editing scroll you are current standing in