Small prototype support
Small prototype support

In the perl conversion script there is no support for perl prototypes like
```
sub otherwise (&;$) {
```
this leads to strange C code like:
```
@fn public method otherwise(&;$)()
```

This leads to problems with the generation and messages like:
```
warning: member with no name found.
```

This proposed patch adds
- detection of prototypes
- use just the prototype definition in case the parameter statement is not used (backward compatibility)
- translating `&` to 'subroutine' (was missing in the list

jordan2175/doxygen-filter-perl