v1.17.8: bug fix patch

• added checks whether files are open for writing
• changed to new defaults: --(cna/baf/snv)-rnd [double:1.0e-6] (nan)
• allowed --cna-jump -1 and --baf-jump -1 (no jumps)
• --cna-jumps [baf-jumps-file] and vice versa enabled (useful for exome data)
• jumps read and integrated with new function match_jumps() (not get_track()).
• fixed bug when chromosomes have no non-zero observations.