* sort: disable support for thousand separators
In order to be compatible with GNU, we have to disable thousands
separators. GNU does not enable them for the C locale, either.
Once we add support for locales we can add this feature back.
* sort: delete unused fixtures
* sort: compare -0 and 0 equal
I must have misunderstood this when implementing, but GNU considers
-0, 0, and invalid numbers to be equal.
* sort: strip blanks before applying the char index
* sort: don't crash when key start is after key end
* sort: add "no match" for months at the first non-whitespace char
We should put the "^ no match for key" indicator at the first
non-whitespace character of a field.
* sort: improve support for e notation
* sort: use maches! macros