[Cpptool-develop] Some bug fixed & enhancement...

[Baptiste L. <gai...@fr...>]

I fixed a few bug:
- Tabulations are now handled correctly in LineBasedTextDocument
- crash on resolving an identifier that as gone out of scope:
{
   int index;
}
index;
=> crashed when attemping to resolve the reference to the local variable
index.

I've also modified the implementation of
VCLineBasedTextDocument::doGetSelectionRange, making for friendly for
undoing (a single undo is now enough to undo the renaming of a given
variable).

Baptiste.