Memory Leak on XojFont

[wbrenna]

If the font size (probably type as well) is changed, it will leak "-1" objects of type XojFont. This does not actually require typing anything in the new or old font.

[andreasb242]

There is a macro "XOJ_INIT_TYPE(SaveJob);" missing e.g. in a copy constructor.

I used this macros because its faster than use e.g. valgrind, and it's always on, also if the user don't mind about it...

The disadvantage is: it has to be inserted in each constructor / destructor.

[wbrenna]

Good call - it's in FontButton when it returns an XojFont without constructing a new one. Fixed...