Remove some places where "znc.conf" is mentioned needlessly

CZNC::ExpandConfigPath() handles an empty string as its argument quite well, so
make all those other places use this.


git-svn-id: https://znc.svn.sourceforge.net/svnroot/znc/trunk@1469 726aef4b-f618-498e-8847-2d620e286838

main.cpp

@@ -140,8 +140,6 @@ int main(int argc, char** argv) {
 
 	if (optind < argc) {
 		sConfig = argv[optind];
-	} else {
-		sConfig = "znc.conf";
 	}
 
 	CZNC* pZNC = &CZNC::Get();