`repr(::Float128)` is broken

[dzhang314]

In Julia, repr(x) is supposed to return valid Julia code that can be executed to reconstruct an object equivalent to x. For example, repr(::Float16) and repr(::Float32) add annotations to x indicating its type:

julia> repr(Float16(1))
"Float16(1.0)"

julia> repr(Float32(1))
"1.0f0"

However, repr(::Float128) fails to do this, and evaluating its result yields a Float64.

julia> repr(Float128(1))
"1.00000000000000000000000000000000000e+00"

julia> 1.00000000000000000000000000000000000e+00 |> typeof
Float64

In particular, repr(::Float128) is completely broken for Inf128 and NaN128, which are currently formatted as inf and nan.

julia> repr(Float128(Inf))
"inf"

julia> repr(Float128(NaN))
"nan"

julia> inf
ERROR: UndefVarError: `inf` not defined

julia> nan
ERROR: UndefVarError: `nan` not defined

These should format as Inf128 and NaN128 (see #83) respectively.