add Householder transformation in C
add solver by Givens rotation
add solver by Givens rotation
add solver by QR factorization with Gram-Schmidt orthonormalization
modify to build solver with QR factorization
add solver by LQ factorization with Gram-Schmidt orthonormalization
add test_agivens_[12]_c to Makefile
merge branch master into householder
merge branch 'master' into gramschmidt