i.e. don't hardcode text attributes

and: * add some flags * document them * move the customizable stuff to defaults.c

when a tab is closed (C-t x 0) the previous one gets selected via switch_to_tab, but the TAB_URGENT flag is kept.

this aims to solve (albeit only partially) the confusion between telescope' ``struct window'' and ncurses WINDOW. It also brings some more emacs-like nomenclature, which may be a good thing.

nodelay conveys better what the function do

After the change to debounce frequent handle_resize, the old hack wasn't working anymore.

it's good for thing like images and text with weird encodings.

and made the cmd_* functions public