i.e. don't hardcode text attributes

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

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.

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

and made the cmd_* functions public

<> → "" and reorder