switched to new EMFGeneratorFragment

Change-Id: I5f89e2394260a5955c5b1cd78e3ce8c9e089375a
issue 2: Check for repeated use without operations

it was only checked for classes, not for traits

Closes #2
 
http://github.com/LorenzoBettini/xtraitj/issues/issue/2

Change-Id: I742ffa3e324d556fb85e11ffc985e17d0b5780a6