Enable wine logging by default when Lutris is started with -d flag

[smichel17]

By default, wine games have wine debug output suppressed (WINEDEBUG="-all"), for performance reasons. This is good.

However, when trying to diagnose a problem, people currently have to enable wine debug output before getting a log with lutris -d. This is particularly clumsy for getting logs when an installer fails, since they need to enable debugging output in the global wine runner settings, affecting all their games if they forget to revert it afterwards.

A compromise would be to enable winedebug output if it is disabled, when starting lutris with -d. This should only be the default — it should not override game specific settings, if they override the default.

[smichel17]

The relevant sections of code seem to be:

• -d arg parsing: https://github.com/lutris/lutris/blob/master/lutris/gui/application.py#L196
• Config file parsing: https://github.com/lutris/lutris/blob/master/lutris/config.py
• Setting the WINEDEBUG env var: https://github.com/lutris/lutris/blob/master/lutris/runners/wine.py#L819

I'm new to both python and the Lutris code base, so I'm not sure exactly which steps should be added where.