Optimization using ByteString

[msakai]

I confirmed Geoff Sutcliffe that TPTP files are always in ASCII. (Current TPTP-v7.3.0.tgz contains some files with non-ASCII characters in UTF-8, but he said he will fix them.)

So it might be possible to use ByteString to improve efficiency:

• read file as lazy ByteString and feed it to Alex directly without going through String (Note that Alex internally uses UTF-8),
• dump formula into bytestring Builder instead of ShowS.