add bhk_irrational()
Update bhk_irrational(): generalize delta to n zigzags
Add drlm_not_extreme_2()
Add phi_s_in_drlm_not_extreme_2(s)
bhk_irrational(): simplify the code using symmetry
Rename gmi_irrational to bhk_gmi_irrational. Generalize and simplify code
(phi_s_in_drlm_not_extreme_2): Add default argument