test cases
xpressn.c, fix semantics of `int(x)' and remove dangerous macros

int(x) most probably shall be trunc(x) instead of floor(x)
  note trunc(x) was #defined beeing floor(x)
  note ln(x) was #defined beeing log(x)
xpressn.c, fix semantics of '^' '**' 'pow' and 'pwr'

these four variants of "x raised to y" deviate in sublte ways
  from the mathematical versions
xpressn.c, extend domain of 'log' and 'sqrt' in a "spicy" way
xpressn.c, fix spicy domain extension of log(x)