Most of these are simple changes. I added an `is_pager_less` and a `get_pager`
function to `pager.sh`. In order for this function to be available for use
inside `pager.sh`, I had to define the functions before setting defaults.
The `is_pager_less` function is then used for the `--search-pattern` to see if
the `$SCRIPT_PAGER` supports the `--search-pattern` flag. Right now, the only
supported pager is `less`.
