list.py: Removed unnecessary calls to gettermsize().
list.py: Extracted duplicate code for listing files in a directory into a utility function.
lists.py: Rewritten list formatting code.

- Split up into functions for distributing the items into columns and actual formatting and printing of the columns.
- Fixes printing when console is narrower than the longest name.
Merge pull request #205 from Feuermurmel/list-fix

Refactoring in the lists module and fix of #198