Code versioning strategy

I was half-way through writing a long-winded explanation when I saw your reply.
As yours is easier to read I will admit surrender :)

One thing which is still worth adding is about merge conflicts.

Merge conflicts occur when a file has changed in both places in a way that Git cannot solve on its own.
For example if we have updated the autoGainMax setting and you have as well.

In this case Git does not know which value to use and you will see something like this:

$ git merge origin/master
Auto-merging Settings.py
CONFLICT (content): Merge conflict in Settings.py
Automatic merge failed; fix conflicts and then commit the result.

Auto-merging is fine, it is just when you see the CONFLICT message that a problem needs to be fixed.

The conflicted file will now have some slightly odd lines, like this:

<<<<<<< HEAD:Settings.py
autoGainMax = 5.0
=======
autoGainMax = 4.0
>>>>>>> origin/master:Settings.py

In this case HEAD is your version, which are all the lines above the ======= mark.
All the lines below the ======= mark are origin/master, our updated version.

Change the file to be correct again by replacing all of the text including the <<<<<<< and >>>>>>> lines with what you want to keep.
Then commit the fix to finish the process:

git commit -a -m 'kept my autoGainMax'

There is a good reference (if a little dry) here: Basic Merge Conflicts.