Member function pointer support

Also adds support for what cglobal is to ccall.
`Member function pointer support

Also adds support for what cglobal is to ccall.
```
    @cxx foo::bar
```
access the global bar in namespace foo. & is supported to get
the address instead, e.g.:
```
    @cxx &foo::bar
```

This makes Qt's new signal/slot syntax work (yay!).