Review Request: Add replace feature to find in files.

[David Nolden]

I've tried this out, overall good work. I agree though with Milians comment.

Possible improvements:
- In the "Find/Replace" dialog, there is a "Search" and a "Replace"
button. The "Replace" button is a bit confusing though, because it
indicates that the replacement will be done directly, without allowing
the user any further interaction.
- Instead of the "Apply" button, I would use a normal button with a
text like "Replace %i occurences in %i files".
- It might be better if the tree-view would show the _replacements_,
rather than the found text, when the corresponding item is checked.

Bugs:
- I have noticed some painting problems in the tree-view, sometimes
some items are truncated vertically
- When using a regular expression template for searching, then the
bold highlighting in the results is applied to the whole range where
the regular expression has been recognized, not only to the text (not
sure whether this can be fixed though, it's a minor thing anyway)

Greetings, David