MiniBASIC update: v0.9.4

I've just updated MiniBASIC to 0.9.4.  This fixes a rather fundamental flaw in the expression parser.  Previously, string values that happened to be valid language tokens like "(" and ")" could get confused with actual language tokens, causing incorrect results.  Fixing that required some fairly deep changes to the parser.

But, it all appears to be working correctly now!  I also took the opportunity to add two more demos:

• demo/othello: another program from the late 80s, ported to MiniBASIC and slightly enhanced.  This is the classic game of "Othello" (aka "Reversi") for 0-2 players.  The AI is slow, but surprisingly strong; I can't beat it myself!
• demo/oddChars: displays a chart of "odd" characters available in MiniBASIC, including the four card suits, six die faces, little stick people, and more.

Remember, MiniBASIC is still brand new; the paint is not dry yet.  If you see something, say something!  (On that score, special thanks to GitHub user eddavis2 for careful testing & reporting of issues found.)