Working update of 1-body changes ... overlap compiles, testing next
Overlap ints tests passed.
Simple API for one-body ints works for overlap only (cartesians only, no derivs, etc.).
HRR-less build of kinetic energy ints implemented.
Nuclear attraction integrals are implemented (one nucleus at a time).
Clarified the source of chebyshev-based Boys
Chebyshev-based Boys can be initialized with negative mmax, this will avoid initialization of the table, etc. Aimed at generic code.
Simple API now can handle nuclear attraction integrals.
TwoBodyEngine works for Coulomb kernel
Moved simple_api.h to cxxapi.h
Pacified warnings about explicit conversion operators in vector_x86.h
New C++ API = bump to 2.1.0; not complete = beta
Merge pull request #9 from evaleev/1body-ints

1body ints + new C++ API implemented (not everything works)