Handle unusual printout order and property chains in 'graph' format

[alex-mashin]

Handle unusual printout order in 'graph' format, i.e., the one with main column absent or not the first printout.

Per @YOUR1: added 'graphfields' parameter (off by default) that switches non-page properties display to labels within nodes from edges.

Property chains are displayed as edges regardless of the type of the last link.

Unit test for the 'graph' format rewritten and extended.

Bug: #742

[codecov-commenter]

Codecov Report

Merging #749 (5511bff) into master (34138f1) will increase coverage by 0.76%. The diff coverage is 25.86%.

@@             Coverage Diff              @@
##             master     #749      +/-   ##
============================================
+ Coverage     39.59%   40.35%   +0.76%     
- Complexity     2054     2061       +7     
============================================
  Files            75       75              
  Lines          7251     7268      +17     
============================================
+ Hits           2871     2933      +62     
+ Misses         4380     4335      -45     

Impacted Files	Coverage Δ
src/Graph/GraphPrinter.php	0.00% <0.00%> (ø)
src/Graph/GraphOptions.php	95.45% <33.33%> (+95.45%)	:arrow_up:
src/Graph/GraphFormatter.php	96.29% <87.50%> (+18.22%)	:arrow_up:
src/Graph/GraphNode.php	100.00% <0.00%> (+22.72%)	:arrow_up:

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[alex-mashin]

This comment is to bring this pull request to the attention of @JeroenDeDauw and @YOUR1.

[YOUR1]

Sorry for the hold up. I've tested it and found no further issues using the default (without |graphfields) graph. Same goes for the new functionality; |graphfields - no issues there aswel. Can be merged!

[alex-mashin]

@JeroenDeDauw?