Improve the runtime performance of ViewFactor

[kbenne]

close #3713

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Time for the test case reference in #3713 is now

kbenne-27067s:OpenStudio kbenne$ time ./build/Products/openstudio build/test.rb
49 view factors => 0.0 sec
64 view factors => 0.0 sec
81 view factors => 0.01 sec
100 view factors => 0.01 sec
121 view factors => 0.01 sec
144 view factors => 0.02 sec
169 view factors => 0.02 sec
196 view factors => 0.04 sec
225 view factors => 0.05 sec
256 view factors => 0.06 sec
289 view factors => 0.08 sec
324 view factors => 0.11 sec
361 view factors => 0.14 sec
400 view factors => 0.18 sec
441 view factors => 0.23 sec
484 view factors => 0.3 sec
529 view factors => 0.4 sec
576 view factors => 0.49 sec
625 view factors => 0.64 sec
676 view factors => 0.76 sec

We can get better but it will require some lower level workspace effort that I will work on and put in a different commit after release.

[jmarrec]

Nice job @kbenne, but this lacks comments. We're doing unusual stuff here, so comments would be nice, added some in #3720