Backport double sided material spec

[iche033]

backport of pull request #410

[codecov-io]

Codecov Report

Merging #418 (0f0ef96) into sdf9 (a0d4807) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             sdf9     #418      +/-   ##
==========================================
+ Coverage   86.42%   86.43%   +0.01%     
==========================================
  Files          60       60              
  Lines        9294     9304      +10     
==========================================
+ Hits         8032     8042      +10     
  Misses       1262     1262              

Impacted Files	Coverage Δ
src/Material.cc	98.07% <100.00%> (+0.13%)	⬆️

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[scpeters]

some odd windows test failures after merging with sdf9:

• https://build.osrfoundation.org/job/sdformat-ci-pr_any-windows7-amd64/1686/testReport/

1: [----------] 2 tests from DOMActor
1: [ RUN      ] DOMActor.LoadActors
  1/172 Test   #1: INTEGRATION_actor_dom ..................................Exit code 0xc0000417
***Exception:   0.09 sec

35: [----------] 1 test from DOMWorld
35: [ RUN      ] DOMWorld.LoadLights
 35/172 Test  #35: INTEGRATION_light_dom ..................................Exit code 0xc0000417
***Exception:   0.08 sec

81: [----------] 5 tests from DOMWorld
81: [ RUN      ] DOMWorld.NoName
81: No HOME defined in the environment. Will not log.
81: [       OK ] DOMWorld.NoName (47 ms)
81: [ RUN      ] DOMWorld.Duplicate
81: [       OK ] DOMWorld.Duplicate (59 ms)
81: [ RUN      ] DOMWorld.LoadIncorrectElement
81: [       OK ] DOMWorld.LoadIncorrectElement (62 ms)
81: [ RUN      ] DOMWorld.Load
 81/172 Test  #81: INTEGRATION_world_dom ..................................Exit code 0xc0000417
***Exception:   0.24 sec

85: [----------] 7 tests from DOMActor
85: [ RUN      ] DOMActor.DefaultConstruction
85: [       OK ] DOMActor.DefaultConstruction (0 ms)
85: [ RUN      ] DOMActor.CopyConstructor
85: [       OK ] DOMActor.CopyConstructor (0 ms)
85: [ RUN      ] DOMActor.CopyAssignmentOperator
85: [       OK ] DOMActor.CopyAssignmentOperator (0 ms)
85: [ RUN      ] DOMActor.MoveConstructor
85: [       OK ] DOMActor.MoveConstructor (0 ms)
85: [ RUN      ] DOMActor.MoveAssignment
85: [       OK ] DOMActor.MoveAssignment (0 ms)
85: [ RUN      ] DOMActor.CopyAssignmentAfterMove
85: [       OK ] DOMActor.CopyAssignmentAfterMove (0 ms)
85: [ RUN      ] DOMActor.Add
 85/172 Test  #85: UNIT_Actor_TEST ........................................Exit code 0xc0000417
***Exception:   0.03 sec

[scpeters]

@osrf-jenkins run tests please

[scpeters]

now the windows build is failing with an internal compiler error:

• https://build.osrfoundation.org/job/sdformat-ci-pr_any-windows7-amd64/1687/

I'm going to take that build machine offline and try again

[scpeters]

@osrf-jenkins run tests please