chore, use generic octlab CFLAGS allowing for both a matlab and octave build
chore, output config.log in case of failure during configure
chore, enable octave/matlab contribs in travis CI build
Merge branch 'contrib/mex-tzconv'

* contrib/mex-tzconv:
  chore, enable octave/matlab contribs in travis CI build
  chore, output config.log in case of failure during configure
  chore, use generic octlab CFLAGS allowing for both a matlab and octave build