Gmsh extension3

[jotaraz]

Most important: Added functions for incomplete grids. (read from gmsh and seal)
Secondly: Added rudimentary functions for mixed grids

[codecov-commenter]

Codecov Report

Attention: 88 lines in your changes are missing coverage. Please review.

Comparison is base (baf258e) 70.83% compared to head (ad712b8) 71.92%.

Files	Patch %	Lines
src/extendablegrid.jl	62.90%	46 Missing ⚠️
ext/ExtendableGridsGmshExt.jl	89.77%	23 Missing ⚠️
src/io.jl	90.55%	12 Missing ⚠️
src/seal.jl	91.86%	7 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##           master      #34      +/-   ##
==========================================
+ Coverage   70.83%   71.92%   +1.09%     
==========================================
  Files          25       26       +1     
  Lines        3761     4082     +321     
==========================================
+ Hits         2664     2936     +272     
- Misses       1097     1146      +49     

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[j-fu]

@cmerdon - could you try this PR ? IMHO it is ok.

[chmerdon]

good, it works for me. However, simplexgrid_from_gmsh seems to generate an ExtendalbeGrids{Float64, Int64} always, there seems to be no way to use Int32. Maybe we want to have that possibility?

[j-fu]

Hm @jotaraz, how does gmsh store integers ? Always as 64bit ?
May be we could add a kwarg indextype which by default would be what gmsh has.

[jotaraz]

@j-fu @chmerdon As far as I know, Gmsh (or at least Gmsh.jl) stores node indices etc. as UInt64 and the coordinates as Float64.

Since the last updates, there is the possibility to construct a grid from a gmsh file (or module) with any desired types for Ti, Tc. The conversion in the other direction (ExtendableGrid -> Gmsh) seems to work already, independently of the type of the ExtendableGrid.

[j-fu]

I would like to make

ExtendableGrids.simplexgrid_from_gmsh
ExtendableGrids.simplexgrid_to_gmsh
ExtendableGrids.mixedgrid_from_gmsh
ExtendableGrids.mixedgrid_to_gmsh

public API for all the gmsh stuff.
Maybe mixed and simplex could be merged.

As for the tests: Gmsh creates different grids on windows...