Add unit-tests for MIN() and MAX() macros

I was going to use them to fix the bug, but found a better solution.
Do not erase anything on curses initialization

It's useless, whole terminal is redrawn after that anyway.
Fix a minor UI glitch at startup

Drawing of rightmost character position of the stat window after
startup.
Remove erasure of all elements on resizing

Seems to be completely useless all elements are redrawn anyway.
Create all windows as 1x1 at 0x0

Completely useless to try give them correct size, it will be done
later during first window redraw operation anyway.

Fixes segmentation fault on OS X, because of creating and filling
window of negative size for small terminals:

    change_win = newwin(20, 30, (screen_y - 20)/2, (screen_x -30)/2);
Extract ui.c:create_windows()

Initializes all WINDOW variables by calling newwin() to create
ncurses windows.
Merge branch 'fix-os-x-small-term-startup-segfault'

Fix a minor UI glitch with drawing rightmost character position of the
stat window after startup.

Fix segmentation fault during startup in a small terminal on OS X.
Thanks to Daniel Dettlaff (a.k.a. dmilith).