maccer has no Makefile

Turns out the whole Makefile is missing.

This works: https://github.com/gheja/gbdk/blob/master/maccer/Makefile

Original:
The maccer Makefile is missing the `clean` rules:

```
/Applications/Xcode.app/Contents/Developer/usr/bin/make -C /Users/matthew/_me/gbdk/gbdk-master/maccer clean
make[1]: *** No rule to make target `clean'.  Stop.
make: *** [maccer-clean] Error 2
```
