amended the rest of reference data for hf and hf++ tests due to switc…

…h to codata2018

building tests requires defining __COMPILING_LIBINT2 also

{set_}scale -> prescale{d}_by

libint_f dependency computation seemed to explode memory consumption …

…by cmake, attempt to fix

reverted d157359 in hartree-fock++.cc

bump to 2.6.0-beta.6 [skip ci]

bump to 2.6.0-beta.5

renamed test-boys in autotools-based build of exported lib

reamended beta.3

bump to 2.6.0-beta.1 done