GSoD week 3

 Hi!

Work is ongoing and I am still mostly focusing on reviewing doxygen blocks in the header files of the 'common' folder.

In the meantime, some things have been merged:

- PR#2361 - documentation generated from the 'common' folder is now nicely structured and divided into groups. Grouping will ultimately be applied to all header files in the project.

- PR#2457 - everyone can now easily build the doxygen documentation using a make command or the provided .sh script (big thanks to Thierry for his help with the scripts)

- PR#2467 - doc edits in header files

- PR#2488 - doc edits in header files

The last two PRs are merged but if you look into them, you'll be able to find my summary of the missing documentation which we haven't yet worked on. There is a lot to add and I can't do it on my own so any kind of help from the development team will be greatly appreciated. Creating developer documentation is always a cooperation between an SME and a tech writer so without you guys my powers are limited :)

During this week I also had a very interesting checkpoint call with my mentor Eugene where we clarified certain aspects of my GSoD project. I won't bore you with details but the scope and priority of tasks is now much better defined and I'm sure it's going to positively affect my progress.