monopam quality: split detect into static / doc / tools (E001/E010)
Brings the cyclomatic complexity of detect down from 14 to single
digits and the nesting of read_policy down from 5 to 2 by extracting
detect_static, detect_doc, detect_lib_tool, detect_tools, read_file,
parse_x_quality_line, and read_policy_from_opam helpers. Behaviour
unchanged.