Large amount of changes:

* First draft of implmenting Qt5 Plugin architecture - Loaders are proper plugins now, but the api sucks -
* replaced a few instances of const char */std::string with QString

* Fix function signature promotion logic:
decompiled code before:
```cpp
int main(int argc, char *argv[], char *envp[]) {
    if ((unsigned int)argc > (unsigned int)0xee6b27ff) {
        proc2();
    }
    if ((unsigned int)argc <= (unsigned int)0xefffffff) {
        proc2();
    }
    if ((unsigned int)argc > 1) {
        proc2();
    }
    if (0 - argc < -2) {
        proc2();
    }
    return 0;
}
```
afterwards:
```cpp
int main(int argc, char *argv[], char *envp[]) {
    if ((unsigned int)argc > (unsigned int)0xee6b27ff) {
        printf("Population exceeds %u\n", (unsigned int)0xee6b2800);
    }
    if ((unsigned int)argc <= (unsigned int)0xefffffff) {
        printf("The mask is %x\n", (unsigned int)0xf0000000);
    }
    if ((unsigned int)argc > 1) {
        printf("Arguments supplied\n");
    }
    if (0 - argc < -2) {
        printf("Three or more arguments\n");
    }
    return 0;
}
```
Merge branch 'qt5_and_boost' of github.com:nemerle/boomerang into qt5_and_boost
Fix MachO plugin.

* add forgotten SymbolTableInterface implementation for MachOBinaryFile