Add branch/path coverage to reports

[dvdoug]

For #380

Hello @sebastianbergmann

This PR:

• Adds new columns for branch and path coverage to the HTML reports when available (I could not see a way to have conditional rule inside the template itself, so have implemented this by duplicating the templates)
• Adds branch and path data to the text report when available
• Adds branch and path data to the clover report where available
• Changes the calculation of CRAP to use path coverage rather than line coverage where this is available to better align with the definition. Interestingly, I've noted this sometimes reduces the score on a partially covered function, it doesn't necessarily increase it.
• Changes the definition of "covered" for a function/method/class to use branch coverage rather than line coverage where this available.

I've opted to use branch coverage rather than path coverage for that last metric because like line coverage, 100% branch coverage is realistically achievable whereas 100% path coverage for non-trivial functions is often not due to the exponential nature of paths. The large number of uncovered paths on such methods then has a disproportionate effect when summing up coverage on larger units like files and directories tending to mark them as uncovered even when most of the other methods and functions actually do have good coverage. This effect doesn't happen with branch coverage so I think it's a good middle ground between lines and paths and the CRAP score will still reveal the many-pathed functions as danger areas and good potential candidates for a refactoring.

[codecov]

Codecov Report

Merging #761 into master will increase coverage by 0.63%.
The diff coverage is 89.28%.

@@             Coverage Diff              @@
##             master     #761      +/-   ##
============================================
+ Coverage     84.55%   85.19%   +0.63%     
- Complexity      894      951      +57     
============================================
  Files            40       40              
  Lines          2584     2809     +225     
============================================
+ Hits           2185     2393     +208     
- Misses          399      416      +17     

Impacted Files	Coverage Δ	Complexity Δ
src/Node/File.php	76.09% <74.04%> (+1.09%)	118.00 <10.00> (+29.00)
src/Report/Text.php	80.23% <82.53%> (+0.90%)	25.00 <0.00> (+3.00)
src/Node/AbstractNode.php	81.48% <100.00%> (+2.75%)	41.00 <4.00> (+4.00)
src/Node/Builder.php	97.14% <100.00%> (ø)	24.00 <0.00> (ø)
src/Node/Directory.php	91.78% <100.00%> (+1.61%)	63.00 <13.00> (+12.00)
src/Report/Clover.php	82.75% <100.00%> (ø)	30.00 <0.00> (ø)
src/Report/Html/Facade.php	94.91% <100.00%> (+0.08%)	7.00 <0.00> (ø)
src/Report/Html/Renderer.php	96.85% <100.00%> (+0.70%)	30.00 <1.00> (+3.00)
src/Report/Html/Renderer/Dashboard.php	99.18% <100.00%> (ø)	32.00 <0.00> (+1.00)
src/Report/Html/Renderer/Directory.php	88.00% <100.00%> (+3.00%)	8.00 <0.00> (+2.00)
... and 3 more

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