Convert from indented if-block to return then unindented code. This should have basically one line change at the top, one line removed at the bottom, and then all whitespace.
Pygments offers great styles and in dark terminals the default is unsatisfactory.
Use two new env variables BASH_IT_CLESS_STYLE and BASH_IT_CCAT_STYLE to select pygment themes.
Availables styles can be listes using pygmentize -L styles
When pygmentize is not installed, the functions less/cat are not
defined, the native commands will be used instead. Also removed the
error message that was shown when the command was not found.
Using `command -v` instead of `which` to check for the existence of the
executable - this works better as it does not print an error message if
the executable is not found.