Fix crash at startup on terminal resize

[zcsahok]

To reproduce the issue

1. start TLF in a resizable terminal with size smaller than 22x80
2. at the "Continue anyway?" prompt resize the terminal
3. get a segfault
   

The issue is caused by resize_layout() trying to access not yet initialized variables (rst arrays).

Solved by introducing variable tlf_initialized that is set to true only when all has been set up, just before calling logit().
While tlf_initialized is false, resizing now just stores the terminal size.

A related issue has also popped up: resizing "keypress" is treated as an actual one, causing misfunction at some "Y/N" or "press any key" prompts.
Terminal resize is now not propagated to the caller of key_get()/key_poll().

[dl1jbe]

Makes sense.
But it seems to someway conflict with the packet screen, especially with the login procedure.
To reproduce unset CLUSTERLOGIN in logcfg.dat an start with packet support. Before entering your password resize the window. Login fails and cluster interface gets deactivated.

[zcsahok]

I got no issue with resize at the cluster login prompt. All worked as without resize.

[zcsahok]

Even the original code can cope with resize at cluster login. Interesting.

[dl1jbe]

I got no issue with resize at the cluster login prompt. All worked as without resize.

Ok, I will dig in what happens here. I would say feel free to merge your PR in in meantime. If its reproducible here I will add another PR later.

Even the original code can cope with resize at cluster login. Interesting.

Yes that worked all the time.