Restore file extensions previously removed to satisfy the Batch Convert pattern box

Now that I use a generic list box instead of VB's built-in file list
box, I can support as many damn formats as I want!
Remove a bunch of DoEvents calls

One of them was potentially causing re-entry errors, but because most
were added when I was a younger programmer who had no idea how DoEvents
actually worked, there was no real need for them.
Fix rendering of preview images from alternate sources
Suppress messages when loading images as necessary

Basically, if a loaded image isn't a "main" image - e.g. one that gets
its own MDI form - don't display any messages.  This allows the new
Batch Process dialog to preview images without requiring any custom
functions.
Fix typo in central error handler
Updated master language file
Further Gaussian Blur optimizations

I was able to cut a further 10% of processing time with another set of
carefully profiled optimizations.  Classic VB is painfully difficult to
optimize on account of its total unpredictability.  So many unrelated
factors affect performance, and looking at the code you'll notice that
some optimizations work in the x-direction but not y (and vice versa).
Strange stuff.

About the only thing left I can do to speed up the function is write a
new Integer-only version.  I'm not sure how worthwhile that would be,
but I may investigate in the future after some other projects wrap up.
Remove an Unload statement that may be causing Out of Memory errors

For now, the Out of Memory error has disappeared, but that doesn't mean
much considering how unpredictable it was.  I'll keep an eye out.
New public constant for timing processing calls

I may extend this as an actual user preference at some point, but for
now it must be set as a compile flag.
Finalize Gaussian Blur optimizations
Redesign Preferences tooltips to better support translation

The translation engine will automatically translate tooltips, but VB
makes it difficult by sticking long tooltips in their custom FRX
resource format.  To ameleoriate the process of translating such
phrases, I instead assign them in code.  This means I no longer have to
make any manual changes to the translation file produced by the
automatic translation file generator.
Completely redesigned mousewheel subclassing

Mousewheel support can now be enabled in the IDE!  Also, it is much less
prone to crashing the compiled EXE.

This may have been the root cause of my random hard-crashes previously.
We'll see if this new system is more robust.
Step 1 of new Batch Process Wizard complete

Steps 2 and 3 are left, but I wanted to commit this as a number of other
very useful (and important) commits have been waiting on it.