Progress bar

[yakir12]

It would be nice to have a progress bar. Something like this maybe:

pb = progressbar(4, widget=builder["a_GtkProgressBar_I_made_in_Glade"])
push!(pb, 2) # half way through!

[yakir12]

Wow, that was a lot easier than I thought (copied what you did with the label widget):

"""
    progressbar(n; widget=nothing, signal=nothing)

Create a progressbar displaying the progress of a process; push to the widget new
iteration integers to update the progressbar. Optionally specify:
  - the GtkProgressBar `widget` (by default, creates a new one)
  - the (Reactive.jl) `signal` coupled to this progressbar (by default, creates a new signal)
"""
function progressbar(n::Int;
               widget=nothing,
               signal=nothing,
               syncsig=true,
               own=nothing)
    signalin = signal
    signal, value = init_wsigval(Int, signal, 0)
    if own == nothing
        own = signal != signalin
    end
    if widget == nothing
        widget = GtkProgressBar()
    else
        setproperty!(widget, :fraction, value)
    end
    preserved = []
    if syncsig
        push!(preserved, map(signal) do val
            setproperty!(widget, :fraction, val/n)
        end)
    end
    if own
        ondestroy(widget, preserved)
    end
    ProgressBar(signal, widget, preserved)
end

I'll wait for the datetimewidget PR (#55, #56, #57) to clear off before I do another PR with this. Don't want to overstep my luck with git :|

[timholy]

Closed by #65