Add test file for wxwidgets configuration, fix found issues and enhance
the cfg a bit:
Fix declarations in comments for wxLog* functions.
Merge the two wxTextFile::Create overloaded function configurations into
one that works for both now.
Removed use-retval attribute from wxBoxSizer::AddSpacer and
wxButton::SetDefault configuration since the functions have side effects
and there is no need to use the return value.
Add some function configurations, the macro _(str) and POD wxLogLevel.