The $ prefix

New features

• Added the $ prefix which returns the value of the current cell
• The r (random) prefix now takes up to two optional prefixes:
  • Without prefixes it returns a random number between 0 (inclusive) and 256 (exclusive)
  • With one integer prefix n it returns a random number between 0 (inclusive) and n (exclusive)
  • WIth two integers n and m it returns a random number between n (inclusive) and m (inclusive)

Minor fixes

• The p (parity) and o (oddity) prefixes now work with two integer prefixes also when the last one is not an integer literal: 3#p will return 1 or 0 depending on whether 3 is divisible by the current tape position