turned out to be a huge performance bottleneck (the text to printed
would always be evaluated, even when it was above the verbosity
level). This reduces fix-ng execution time by over 50%.
gprof(1) is very useful. :-)
The ATerm library doesn't search the heap for pointers to ATerms
when garbage collecting. As a result, C++ containers such as
`map<ATerm, ATerm>' will cause pointer to be hidden from the garbage
collector, causing crashes. Instead, we now use ATermTables.