DocExtract: several improvements

* Accepts Publications as reference section.

* Refactors book handling and search.
  (closes #959)

* Daemon extracts all added pdfs.

* Correctly handles PDF/A files.

* Adds LIGO and LHCP report numbers to the kb.

* Adds the filename of the extracted files in the 999C6f field.

* Converts arxiv urls to report numbers

* Adds support for hdl identifiers.

* Sets a priority on which title form is the most important.
  References will be given priority over anything else while Reference
  will rank last with Bibliography in between.
  That means that if "Bibliography" is found in the text, we assume it is
  the reference section and we don't look for a section titles "Reference".

* Improves error message when pdftotext is missing.

Signed-off-by: Alessio Deiana <alessio.deiana@cern.ch>
Tested-by: Samuele Kaplun <samuele.kaplun@cern.ch>
1: D100 Docstring missing
4: I102 copyright year is outdated, expected 2014 but got 2011
33:35: E126 continuation line over-indented for hanging indent
44: D202 No blank lines allowed *after* function docstring, found 1
44: D400 First line should end with '.', not ')'
67: D400 First line should end with '.', not ')'
87: D103 Docstring missing
105: D400 First line should end with '.', not 's'
126: D400 First line should end with '.', not 'n'
126: D205 Blank line missing between one-line summary and description
126: D208 Docstring is over-indented
137: D401 First line should be imperative: 'Compare', not 'Compares'
137: D200 One-line docstring should not occupy 2 lines
154: D301 Use r""" if any backslashes in a docstring
154: D400 First line should end with '.', not 's'
154: D205 Blank line missing between one-line summary and description
154: D208 Docstring is over-indented
170: D301 Use r""" if any backslashes in a docstring
170: D400 First line should end with '.', not 't'
170: D205 Blank line missing between one-line summary and description
170: D208 Docstring is over-indented
189:29: E126 continuation line over-indented for hanging indent
210:46: E127 continuation line over-indented for visual indent
212:45: E127 continuation line over-indented for visual indent
218: D400 First line should end with '.', not 's'
218: D205 Blank line missing between one-line summary and description
218: D208 Docstring is over-indented
261: D400 First line should end with '.', not 'n'
261: D205 Blank line missing between one-line summary and description
261: D208 Docstring is over-indented
297:15: E121 continuation line under-indented for hanging indent
301:15: E127 continuation line over-indented for visual indent
312:50: E127 continuation line over-indented for visual indent
315:59: E127 continuation line over-indented for visual indent
317:59: E128 continuation line under-indented for visual indent
318:59: E127 continuation line over-indented for visual indent
321:54: E111 indentation is not a multiple of four
321:54: E113 unexpected indentation
322:54: E111 indentation is not a multiple of four
322:54: E113 unexpected indentation
323:54: E111 indentation is not a multiple of four
323:54: E113 unexpected indentation
324:54: E111 indentation is not a multiple of four
324:54: E113 unexpected indentation
326:54: E111 indentation is not a multiple of four
326:54: E113 unexpected indentation
327:54: E111 indentation is not a multiple of four
327:54: E113 unexpected indentation
329:54: E111 indentation is not a multiple of four
329:54: E113 unexpected indentation
330:54: E111 indentation is not a multiple of four
330:54: E113 unexpected indentation
331:54: E111 indentation is not a multiple of four
331:54: E113 unexpected indentation
333:54: E111 indentation is not a multiple of four
333:54: E113 unexpected indentation
334:54: E111 indentation is not a multiple of four
334:54: E113 unexpected indentation
341:17: E127 continuation line over-indented for visual indent
347:24: E111 indentation is not a multiple of four
347:24: E113 unexpected indentation
348:24: E111 indentation is not a multiple of four
348:24: E113 unexpected indentation
349:24: E111 indentation is not a multiple of four
349:24: E113 unexpected indentation
350:24: E111 indentation is not a multiple of four
350:24: E113 unexpected indentation
370:34: E127 continuation line over-indented for visual indent
392:38: E127 continuation line over-indented for visual indent
429:23: E203 whitespace before ':'
439: D400 First line should end with '.', not 'a'
439: D205 Blank line missing between one-line summary and description
439: D208 Docstring is over-indented
456: D400 First line should end with '.', not 'e'
482: D103 Docstring missing
492:53: E203 whitespace before ':'
513: D103 Docstring missing
523:53: E203 whitespace before ':'
533:72: E227 missing whitespace around bitwise or shift operator
545: D103 Docstring missing
555:53: E203 whitespace before ':'
580: D400 First line should end with '.', not 'e'
616: D103 Docstring missing
620: D103 Docstring missing
635:62: E127 continuation line over-indented for visual indent
645:61: E127 continuation line over-indented for visual indent
653: D103 Docstring missing
661: D103 Docstring missing
690: D400 First line should end with '.', not 's'
690: D205 Blank line missing between one-line summary and description
690: D208 Docstring is over-indented
755:14: E127 continuation line over-indented for visual indent
775: D103 Docstring missing
784:49: E227 missing whitespace around bitwise or shift operator