Resize terminal to its original size after :help

This solution is a workaround for strange behaviour of pdcurses library
for this case: the window is resized correctly at first, but changes its
size back on wrefresh(...) call.

Thanks to filterfalse.
Fix resetting of 'lines' and 'columns' options

To their default values.

The previous implementation didn't take into account that corresponding
fields of the cfg structure have incorrect default values.  So new
implementation adds additional fields to the status structure, which
hold initial geometry of the terminal remembered after first redraw
operation.

Thanks to filterfalse.
Add several Windows related TODO items
Merge branch 'win-fix-ui-redraw-after-help'
Update NEWS file
Version v0.7.5
Merge branch 'release-0.7.5'