fix issue #168 (32-bit memory leak reporting)
fix issue #4 (early return)
fix issue #169 (segfaults with show)
fix issue #170 (overMonad)
fix issue #171 (complie on NetBSD)
fix issue #140 (scan noun left argument)
Merge pull request #172 from tavmem/master

fixes for issues #4, 140, 168, 169, 170, 171