Bug: hgattic should ignore diff options

[Hans Meine]

Hi Augie, 

I repeatedly fell into the trap that histedit seems to think that "hg diff" 
outputs something that fully represents a file's changes.  However, I have 
this in .hgrc:

[diff]
# show renames in diffs, too:
git=True
showfunc = True
#ignorewsamount = True
ignorews = True
ignoreblanklines = True

In particular, the last two lines make a big difference (at least for python 
code); I see this as the difference between a user-oriented diff (see above) 
and patch-oriented diff (which must not ignore whitespace).

To be explicit: with the above configuration and current histedit, I often 
have exceptions like this after a simple changeset reordering:

|  File "foo-gui", line 433                                                                      
|    result = ... 
|         ^                                                                                       
|IndentationError: expected an indented block                                                     

Sorry for not providing a patch (yet),
  Hans