Handle :window_size message (#46)

[honsq90]

I'm having issues running the tests locally at the moment.

I was hoping of doing an assert via. Any ideas?

assert_receive {:tty_data, "\e[33m\e[36mSome message about changing window size\e[0m\e[33m\e[0m\r\n"}

[mobileoverlord]

Thanks for submitting this, its looking great. I am going to try to give things a spin locally.

[jjcarstens]

When you change the window size, it will attempt to adjust any current line in the buffer and move the cursor back where it should go. With an empty line waiting for input, it would look something like this:

iex(1)> {:ok, iex_pid} = ExTTY.start_link(handler: self(), type: :elixir)                              
{:ok, #PID<0.449.0>}

# Increase width 10 columns
iex(2)> ExTTY.window_change(iex_pid, 90, 80)
:ok

iex(3)> flush
{:tty_data, "\e[8Diex(1)>                     \e[20D"}

Also, if the width is the same, it returns the empty buffer:

iex(4)> ExTTY.window_change(iex_pid, 90, 80)
:ok
iex(5)> flush
{:tty_data, ""}

[fhunleth]

@jjcarstens Can this be merged?