[it] Reviewed chapter2

Reviewed "Limiting Log Output"
[it] Reviewing chapter2

Reviewed "Using a GUI to Visualize History"
[it] chapter6

Translated "Issues with Submodules"
[it] chapter6

Cosmetic review
[it] chapter6

Added source text in english, to translate into italian
Merge pull request #730 from daftano/master

[it] updated chapter 2 and 6