fixed bug with variable defined as "long" that should be "int" in EM engine

fixed bug with variable defined as "long" that should be "int" in EM engine

- this was apparently overseen when fixing the R'n'D code for 64-bit systems
  back in 2011 by replacing all "long" with "int" types (see commit 61c3da0)
- this bug was open to the public since version 3.3.1.0 was released in 2013
- this bug has potentially broken all EM engine tapes containing amoeba
- fixing this bug potentially breaks similar tapes between 2013 and now
- tapes created before 3.3.1.0 and broken due to this bug should work again