Broadcasting with IdOffsetRange seems wrong

[yha]

This seems fine, although the error message is a bit odd:

oa = OffsetArray(1:4,1)
axes(oa .+ 1)  # (2:5)
oa .+ (1:4)   # 
DimensionMismatch("arrays could not be broadcast to a common size; got a dimension with lengths 4 and 4")

But:

oa_axes = axes(oa)[1]  # 2:5
axes(oa_axes)  # (2:5)
axes(oa_axes .+ 1)  # (Base.OneTo(4))
oa_axes .+ (1:4)  #  3:2:9

I would expect oa_axes to behaves like oa in broadcasting.

[johnnychen94]

+-*/ of two IdentityUnitRange isn't an IdentityUnitRange anymore, and that's the same fact for IdOffsetRange.

julia> Base.IdentityUnitRange(2:5) .+ (1:4)
3:2:9

But oa_axes .+ 1 should preserve the offset. #105 fixes this.

[timholy]

See JuliaLang/julia#30950. That was starting to go a in a scary breaking direction, that effort needs to be restarted with a more careful design.

[yha]

Closing since this is fixed by #114.