Blas/Lapack API: add lapack routines for Cholesky family functions

doc/user/chapters/using.org

lapack_api/CMakeLists.txt

lapack_api/include/chameleon/chameleon_zlapack.h

lapack_api/src/lapack_zhemm.c

lapack_api/src/lapack_zher2k.c

lapack_api/src/lapack_zherk.c

lapack_api/src/lapack_zlacpy.c

lapack_api/src/lapack_zlaset.c

lapack_api/src/lapack_zlauum.c

lapack_api/src/lapack_zposv.c

lapack_api/src/lapack_zpotrf.c

lapack_api/src/lapack_zpotri.c

lapack_api/src/lapack_zpotrs.c

lapack_api/src/lapack_zsymm.c

lapack_api/src/lapack_zsyr2k.c

lapack_api/src/lapack_zsyrk.c

lapack_api/src/lapack_ztrmm.c

lapack_api/src/lapack_ztrsm.c

lapack_api/src/lapack_ztrtri.c

testing/testing_zposv.c