Bigger integers in generators show failing tests

Show failing test for issue #5

* Make `big()` generate bigger numbers
* Add `big()` to `simple_types/0`
* Increase number of tests to 2000 (the `prop_sort` test was not
consistently failing at 1k tests)

This commit should show that there are current three failures with
bigger integers: `prop_sort`, `prop_sort_sb32` and `prop_sort_hex`.

Note this file also seems to use Windows (CRLF) line endings, so I continued
in that fashion.