v0.1.2.1: fix and revise __blscd_p_mark_go_down() and __blscd_p_mark_go_up()
v0.1.2.2: revise __blscd_p_mark_go_down()
v0.1.2.3: fix __blscd_p_draw_screen_lines()
v0.1.2.4: revise __blscd_p_mark_go_down() and __blscd_p_mark_go_up(