Support for pointer types

[blakejohnson]

The thing which is blocking conversion of the HDF5 module to the new StrPack is lack of support for pointer types. I thought that this was specific to Ptr{Void}, but it is also true of any pointer type. For instance:

@struct type Foo
    a::Int64
    b::Ptr{Uint8}
end
f = Foo(1, convert(Ptr{Uint8}, uint8(1))
io = IOString()
pack(io, f)

Also fails. The issue seems to be at line 214 in StrPack.jl, because map() is not defined on pointers.

[pao]

Thanks. This is the next thing on my to-do list, but writing a test for Ptr is kind of difficult since they can't be constructed. I need to dig around to find a convenient jl routine in the C library that can give me one to work with.