commitmonitor Code

* Refactor the child window positioning code out from OnLButtonUp() into PositionChildWindows()
* Store/Restore the slider positions on dialog show/hide.

This implements issue #32.

Improve the diff function if TortoiseSVN is installed:
* if TSVN is installed, add a second entry to the log list control context menu for diffing with TSVN.
* if TSVN is installed, the default diff uses TSVN.
* to get the unified diff again (if TSVN is installed), the log list control context menu entry "show unified diff" has to be used.

This implements issue #13 (kind of).

Select the first url which has unread items when the main dialog is shown.
This implements issue #12.

Instead of showing a message box with the latest error message, show the error text in the revision list control. A doubleclick on the error message clears it and lets the user see the previously fetched log messages.

This implements issue #3.

Indicate the GPL license.

Use custom icons for the tree view, not the ones from the system image list.

Add a button to fetch the latest commits on request.

Show diff on doubleclick.

Show folder icons in the url treeview.

* subclass the tree view control to catch the WM_SETFOCUS message and set the state of the remove button
* use member variables for the HWNDs of the dialog controls