More elegant version of groupConsec.
More efficient version of groupConsec.
Made circa field of RefDate a Bool.
Util:  parseBool also handles String values that can be interp as Bool.
Util, parseBool: Don't coerce String to Bool.
Handle 'circa' with 'date-parts'.

Makes uncertain-dates test pass.
Empty locator label defaults to "page".

Fixes
citeproc-test/processor-tests/machines/integration_IbidWithDifferentLocators.json
test-citeproc:  If full paths given in arguments, find files there.

Otherwise try to match tests in the standard test directory.
Improved concatenation of Formatted items.

Now a trailing space before punctuation is collapsed.
Added a comment.
Changed types in Agent from Literal to Formatted.
Minor code cleanup.
Disamb:  Consider names too when determining date disambiguations.

Previously if you had two distinct names needing disambiguation for
the same date, the letters would not start over with 'a' for the second
name.  Test case (from Nick Bart):

```
@item1, @item2, @item3, @item4

---
references:
- title: Title one
  id: item1
  issued:
    year: 2003
  author:
    given:
    - Al
    family: Author
  type: article-journal
  language: en-US
- title: Title two
  id: item2
  issued:
    year: 2003
  author:
    given:
    - Al
    family: Author
  type: article-journal
  language: en-US
- title: Title three
  id: item3
  issued:
    year: 2003
  author:
    given:
    - Al
    family: Buthor
  type: article-journal
  language: en-US
- title: Title four
  id: item4
  issued:
    year: 2003
  author:
    given:
    - Al
    family: Buthor
  type: article-journal
  language: en-US
...
```
Improved disambiguation.

Now we correctly handle the case with no author but title.
Text.CSL.Proc.Disamb:  Correct definition of allTheSame.
Util: Export tr' and init'.
Text.CSL.Eval.Date:  Fixed bugs with date ranges.

Ranges within the same year were raising an error "Prelude.init: empty
list."

Closes #7.
Added tests for issue 7.
Removed extra copy of chicago-author-date.csl.
Updated chicago-author-date.csl in tests.