I initially forgot to add broadcastprofile.cpp into the list
of source files in build/depends.py, so I didn't noticed all the
errors and mistakes I've made while writing this earlier.
This commit aims to fix these errors and have the BroadcastProfile
class to build.

No idea if this works. I just want to make sure it is saved
somewhere out of my computer.
I may squash this with other commits later.

Both ways didn't handled the document's root tag.
Now, profile values are saved properly.

…ast-profiles

This isn't needed in the current state of the code.

These additions automatically fetches existing
Live Broadcasting preferences from mixxx.cfg, puts
them in the Default Profile and removes the now
useless keys from mixxx.cfg

Add more tests in the process, because the regex changed.

…t call

BroadcastProfile notifies name changes to BroadcastSettings with Qt's signals &
slots system. However Qt is not compatible with the std::unique_ptr smart
pointer. A refactor of BroadcastProfilePtr is required to make it compatible.
std::unique_ptr has been replaced with QSharedPointer, as this type is easy
to pass around in the code while keeping a reference to the original pointer
and deleting it when not used anymore.