aspace2alma: subdivide subject headings

[regineheberlein]

the come out subdivided by "--" only

[regineheberlein]

From Don via Mark: assign $x if it doesn't start with a number:

segments = heading.split('--')
  segments.each { |s| s.strip! }
  subfa_text = segments[0]
  field.append(MARC::Subfield.new('a', subfa_text))

segments[1..-1].each do |segment|
    code = segment =~ /^[0-9]{2}/ ? 'y' : 'x'
    field.append(MARC::Subfield.new(code, segment))
  end
  field.subfields[-1].value << '.' unless ['?', '-', '.'].include?(field.subfields[-1].value[-1])

[regineheberlein]

umbrella issue: #2

[regineheberlein]

QA:

distinct-values(//datafield[matches(@tag, '^6')]/subfield[matches(., '--')]/../@tag)

--> 600, 655

[regineheberlein]

also 700