stdin Support

This release adds support for piping programs to ti842py's stdin. The files can be 8Xp files or plain text files, just like normal

$ cat BAR.8Xp | ti842py --run
$ ti842py -o bar.py < BAR.8Xp
$ cat CLOCK.bas | ti842py -nr
$ ti842py --no-fix-floating-point --run < CLOCK.bas