Massive debugging in lttv filter core:

Massive debugging in lttv filter core:
- for tree construction
- for lttv simple expression assignation

Still to do:
- seg fault occuring when loading trace with the actual tree
- changing op functions (type conversion)
- look for memory assignation whithin the tree

git-svn-id: http://ltt.polymtl.ca/svn@907 04897980-b3bd-0310-b5e0-8ef037075253