Removed boosts (replaced with equivalent on std 14/17/20)
With this modification, there are only 16 libs for the project to add, simplifying a lot.
So two additional libraries will be needed to compile: asio,
nlohmann-json
I also removed OTGZ support by default and disabled it, making it optional (needs to be enabled). Anyone who wants to use it will need to activate this, I think it's ideal since few should use it, so a majority don't use it, which is fairer that those who need to activate it to use it than those who don't need to have this in their program.
Removed libxml2 to use pugixml.
Fixed a bug with the progress bar.
Changed some things in most xml files that pugixml did not like.
Updated the Visual Studio project.
Any NULL symbol has been changed to nullptr.
This most probably broke the CMake that was recently added.
And probably some other things.
Clean git repository since the old svn / git mess was pretty much
unrecoverable unfortunetly. I would have liked to keep the history
for posterity, but that proved to be a futile quest.
