CellReference origin is unitless

[mtfang]

Causes flatten! method to fail (dimension incompatibility error) when flattening CellReferences

[mtfang]

Temporary workaround: Explicit definition of CellReference origin

CellReference(cell, Point(0μm, 0μm))

[ajkeller34]

Working on a fix now. To reproduce the error:

julia> using Devices, Devices.PreferMicrons, FileIO

julia> c = Cell("main", nm)
Cell "main" with 0 els, 0 refs

julia> c2 = Cell("test", nm)
Cell "test" with 0 els, 0 refs

julia> render!(c2, Rectangle(1μm, 2μm))
Cell "test" with 1 els, 0 refs

julia> push!(c.refs, CellReference(c2))
1-element Array{Devices.Cells.CellRef,1}:
 Devices.Cells.CellReference{Float64,Devices.Cells.Cell{Quantity{Float64, Dimensions:{𝐋}, Units:{nm}},Devices.GDSMeta}}(Cell "test" with 1 els, 0 refs, (0.0,0.0), false, 1.0, 0.0)

julia> flatten!(c)
ERROR: DimensionError: 0.0 nm and 0.0 are not dimensionally compatible.
...

The error is slightly different if the referenced cell is empty:

julia> c = Cell("main", nm)
Cell "main" with 0 els, 0 refs

julia> c2 = Cell("test", nm)
Cell "test" with 0 els, 0 refs

julia> push!(c.refs, CellReference(c2))
1-element Array{Devices.Cells.CellRef,1}:
 Devices.Cells.CellReference{Float64,Devices.Cells.Cell{Quantity{Float64, Dimensions:{𝐋}, Units:{nm}},Devices.GDSMeta}}(Cell "test" with 0 els, 0 refs, (0.0,0.0), false, 1.0, 0.0)

julia> flatten!(c)
ERROR: MethodError: no method matching Devices.Cells.Cell(::String, ::Array{Devices.Cells.CellPolygon{_,Devices.GDSMeta} where _,1})
...

[ajkeller34]

Fixed, tests added.