for the first time run under valgrind, found and corrected a bug in the curve refinement routine, which is a very careless piece of coding

RNG API in libtrivia has changed

Imposing -Werror.
Got rid of warning from xax_lex.cpp (%option nounput)

in doing so, correct two more bugs:
- access to non-existent element of MOM could cause segfault
- mfj took Z from wrong input file, which caused crash when merging just 1 file
merging just 1 file now works, then forbidden

rather, I would need Ruby's each_with_index.

first use of C++ ranged for loop in mem.cpp

result: missing doxygen links neither due t extension .hpp, nor to ".." vs <..>