refactor bounding box for cata_tiles::draw

Removed terrain_term_x and terrain_term_y because cata_tiles used its own logic to determine the values instead of letting game::init_ui taking care of it.
They were used in two places: to determine screentile_* and to calculate the size of the drawing area when calling cata_tiles::draw.
The second usage has been replaced with referenced to the width/height of game::w_terrain. Those values are always initialized correctly in game::init_ui.
The first usage has been replaced with the usage of the height/width parameters given to the draw function.
call game::init_ui on zooming

init_ui resets and recalculates the sizes and offsets of the windows, especially the w_terrain window.
Beaus cata_tiles is now invoked with size/offset from that window it draws the resized/zoomed content properly.
remove unused parameter from cata_tiles draw functions

is_at_screen_position is always used with the value false
move a debug message out of the drawing code

Getting a debug message on each draw call would be very annoying.