[WIP] Graph Concepts and Containers

[fuchsto]

As the STL has no equivalent, I defined the DASH graph concepts following the Boost Graph Library (BGL). In his Master thesis, @stiefn refined and extended concepts for several peculiarities and requirements of PGAS and DASH. This merge contains his reference implementation. Merging current development was surprisingly non-conflicting. The implementation proved stable and effizient in several productive scenarios like BFS and Connected Components.

Missing: more unit tests, review, some suggestions for improvement in comments here and there.

[codecov[bot]]

Codecov Report

Merging #634 into development will increase coverage by 0.65%. The diff coverage is 95.24%.

@@               Coverage Diff               @@
##           development     #634      +/-   ##
===============================================
+ Coverage        85.08%   85.74%   +0.65%     
===============================================
  Files              336      355      +19     
  Lines            24954    26570    +1616     
  Branches         11338    12040     +702     
===============================================
+ Hits             21232    22782    +1550     
- Misses            3692     3771      +79     
+ Partials            30       17      -13

Impacted Files	Coverage Δ
dash/test/algorithm/ConnectedComponentsTest.h	100% <100%> (ø)
dash/include/dash/memory/GlobHeapLocalPtr.h	95.65% <100%> (+0.06%)	:arrow_up:
dash/include/dash/memory/GlobHeapCombinedMem.h	100% <100%> (ø)
dash/include/dash/graph/VertexIterator.h	100% <100%> (ø)
dash/test/algorithm/MinimumSpanningTreeTest.h	100% <100%> (ø)
dash/include/dash/memory/GlobHeapCombinedPtr.h	100% <100%> (ø)
dash/include/dash/graph/OutEdgeIterator.h	100% <100%> (ø)
dash/include/dash/graph/EdgeIterator.h	100% <100%> (ø)
dash/include/dash/graph/InEdgeIterator.h	100% <100%> (ø)
dash/test/container/GraphTest.h	100% <100%> (ø)
... and 33 more

[fuchsto]

@stiefn @fuerlinger @rkowalewski @devreal @pascalj

Graph containers and algorithms are fully merged now, including tests and examples. Algorithms are Minimum Spanning Tree and Connected Components.

Relevant implementation is in:

• dash/graph
• dash/algorithms/graph

Integration tests passed, but could use some more unit tests.

Still, I'm voting for merging it into development, that's what the branch is about.

[devreal]

I will give the review a try tomorrow on the train.