extensions: `hash-count` only available on guile 2.0.9

- provide backward compatibility wrapper for hash-count
- remove tabs added in smartprompt.scm code
- standardize on 80column when possible
Fix counting messages mistake introduced in a recent commit : the new hash-count function needs (const #t) instead to count all elements in the hash table
Do not display contacts status & presence update when quiet mode is selected
Merge pull request #15 from vadmeste/master

Do not display contacts status & presence update when quiet mode is selected