The new option 'set selectedcolor' applies to marked text, to the
currently selected file in the file browser, and to the highlighted
match during interactive search-and-replace.
Extend get_softwrap_breakpoint() to break softwrapped lines on
whitespace when a flag is set. This flag is controlled by the new
rcfile option "atblanks". The '>' characters marking two-column
characters at the edge of the screen are disabled when it's on.
If get_softwrap_breakpoint() can't find whitespace in screen range, it
will break the line on the screen edge. (In this case, a blank can be
on the last column of the screen, but text can't, so that a blank on the
last column doesn't become invisible and possibly break the display.)
This fulfills https://savannah.gnu.org/bugs/index.php?49959.
Requested-by: Nicholas Boel <axxisd@gmail.com>
Negative arguments of 'fill' are bright green since a few commits.
So now color all valid numeric arguments in that same style -- the
yellow was hard to see on a dark background anyway.
Also, color a zero tabsize as invalid.
