Change initial state of LZSS buffer from 0x00 to 0x20.

This makes the CIFLIST file look saner (considering the text-file style
octothorped comments, the fact that a bunch of ' ' instead of '^@' makes
for an aligned list, and some entries in the list sometimes having a
space or two after them anyway)

Additionally, some affected .tga files have slight pixel changes (the
correctness of which can only be proven by painstakingly comparing
images to the game's rendering), and some S*.dat files have spaces where
there were nulls before, within pieces of text (e.g. "STUDIO^@DAY" ->
"STUDIO DAY")

Starting off with spaces instead of nulls seems to be correct, but of
course there's a chance that CIFLIST really was supposed to be filled
with nulls all along :) .

Oh, and this change required a change in the file extension collection
process for CIF TREE extraction.