#23 allow a diff between download and the current version

[Anonymous]

Pibber wrote :
The program compares the current contents of the Sims
Download directory,
with the latest version of what it thinks should be
there, and produces a list
of missing / added files, allowing the user to quickly
recover file(s)
inadvertantly deleted, or to copy added files to the
Repository.

[Nobody/Anonymous]

Logged In: NO

a diff list is how I imagine it with differant state in the
download file list :
- present in the repo and with a good version
- deprecated (a newer version exist in the repository)
- missing in the repo
- not install according to the last download version

[Nicolas Chalumeau]

Logged In: YES
user_id=844527

i introduce some history package that need to be refactore
in the ts2-pm-versioning module