patched to compile with QT 4.6.x

There's also some changes in `src/shared/zncmanager.h`:

```
#if QT_VERSION >= 0x040700
#include <QElapsedTimer>
#else
#include <QTime>
#endif```
+++
```
        #if QT_VERSION >= 0x040700
        QElapsedTimer timestamper;
        #else
        QTime timestamper;
        #endif```

and in `src/shared/zncmanager.cpp`:

```
    #if QT_VERSION >= 0x040700
    d.timestamper.invalidate();
    #else
    d.timestamper = QTime();
    #endif```
+++
```
void ZncManager::onConnected()
{
    #if QT_VERSION >= 0x040700
    d.timestamper.invalidate();
    #else
    d.timestamper = QTime();
    #endif
}```