get rid of piForeach

apply some code analyzer recommendations
ICU flag now check if libicu exists
prepare for more accurate growth of containers (limited PoT, then constantly increase size)

libs/main/system/piplugin.cpp

@@ -457,7 +457,7 @@ void PIPluginLoader::mergeStatic() {
 PIStringList PIPluginLoader::pluginsDirectories(const PIString & name) {
 	static PIStringList dl({".", "./plugins", "../PlugIns"});
 	PIString ret;
-	piForeachC(PIString d, dl) {
+	for (const auto & d: dl) {
 		PIString dp = d + "/" + name;
 		if (PIDir::isExists(dp)) ret += dp;
 	}
@@ -470,8 +470,8 @@ PIString PIPluginLoader::findLibrary(const PIString & path) {
 	static const PIStringList suffixes({"", libExtension()});
 	PIFile::FileInfo fi(path);
 	PIString dir = fi.dir(), name = fi.name();
-	piForeachC(PIString & p, prefixes) {
-		piForeachC(PIString & s, suffixes) {
+	for (const auto & p: prefixes) {
+		for (const auto & s: suffixes) {
 			PIString fn = dir + p + name + s;
 			if (PIFile::isExists(fn)) return fn;
 		}