Make Qmake copy res directory instead of OS scripts

Since Qt 5.6 Qmake has supported the (undocumented) file_copies
function.

Moving to an OS independent version is superior for obvious
reasons.

Use in
https://stackoverflow.com/questions/3984104/qmake-how-to-copy-a-file-to-the-output/54162789#54162789

Uses the same interface as the INSTALLS function described here
https://doc.qt.io/qt-5/qmake-advanced-usage.html#installing-files

Implemented in the file_copies.prf file found here
https://code.qt.io/cgit/qt/qtbase.git/log/mkspecs/features/file_copies.prf

advancedSettings.pro

@@ -1,5 +1,5 @@
 QT       += core gui qml quick multimedia widgets
-CONFIG   += c++1z
+CONFIG   += c++1z file_copies
 
 DEFINES += ELPP_THREAD_SAFE ELPP_QT_LOGGING ELPP_NO_DEFAULT_LOG_FILE
 
@@ -43,3 +43,9 @@ win32-clang-msvc{
 include($$include_dir/sources.pri)
 
 include($$include_dir/resources.pri)
+
+# Copy extra files
+COPIES += resCopy
+
+resCopy.files = src/res/*
+resCopy.path = $$OUT_PWD/$$DESTDIR/res