Fix save-stream buffer sizes

[mischa85]

Four small fixes in the save stream (CStreamClass, LZOPipe/LZOStraw):

• The compressed-output buffer is 64 KB, but LZO output can grow to ~68.7 KB
  on incompressible input. That's a heap overrun that has been in the game since
  1999, masked only because game state compresses well.
• The final block's header claims 64 KB uncompressed even when partial, masked by the reader stopping at the content length.
• Both LZO dictionaries are allocated as 64*1024 instead of
  LZO1X_MEM_COMPRESS (16384 * sizeof(lzo_byte *)).

[mischa85]

Superseded by #104. Same five commits, moved off my fork's main onto a topic branch.