Added a check for allready freed in wrenFreeVm.
Added a check for allready freed in wrenFreeVm.

If wrenFreeVm was called twice, this would lead to an error, because the memory was allready freed.
The used check is rather naive, suggesting that a valid vm does have at least one methodName set.

Rohansi/wren,minirop/wren,Nave-Neel/wren,munificent/wren,foresterre/wren,Nave-Neel/wren,Nelarius/wren,bigdimboom/wren,Nelarius/wren,munificent/wren,minirop/wren,Rohansi/wren,Nelarius/wren,Rohansi/wren,bigdimboom/wren,foresterre/wren,munificent/wren,minirop/wren,munificent/wren,munificent/wren,foresterre/wren,Rohansi/wren,minirop/wren,minirop/wren,foresterre/wren,bigdimboom/wren,Nelarius/wren,munificent/wren,Nave-Neel/wren,Nelarius/wren,Nave-Neel/wren,foresterre/wren,bigdimboom/wren