libcint

Merge pull request #1 from maxscheurer/feature/issue-2-int3c1e-second-derivatives

Improve int3c1e hessian tests: high-l basis, ctypes tests, docs

Add int3c1e second-derivative integrals (ipip1, ip1ip2, ipvip1, ipip2)

chore: open PR for int3c1e second-derivative integrals

typo