Placeholder commit for new theme editor

I'm postponing further work on themes until I've finished up the pdLabel
control, as I don't want to do further UI work using the default VB
label.  (That just creates more work for me down the road.)
fxPreview: fix disappearing cursor issue

Also, move all mouse events to pdInputMouse, so we can take advantage of
all the nice benefits it provides
Close All: fix misreported image count
Button Strip UC: remove unneeded subclasser
pdLabel: first draft of Unicode and theme-compatible label control

As the most prolific control in PD, labels present a particular problem
for Unicode support.  Replacing all instances of VB's default label is a
huge undertaking (ugh), and the many ways in which labels are used
throughout the project makes it crucial that our replacement covers all
possible use cases, including all the weird hoops we have to jump
through for run-time language translations.

Making matters worse, the "autosize" property of labels - while helpful
- is a real nightmare to handle manually, particularly for right-aligned
text.  Autosizing right-aligned text requires us to shift the label's
left position, but because VB doesn't expose .Left or .Top properties,
we're stuck using the Extender to do this, and the Extender is prone to
all kinds of weird behavior in the IDE vs compiled.  (Normally I
couldn't care less about IDE behavior for PD's UCs, but in the case of
labels, the IDE is actually quite helpful for getting positioning
right.)

I *think* I've finally worked through all these various issues for the
main case of non-wordwrapped, left/center/right-aligned labels, so I'm
content to commit this first draft of the label control.  I want to do a
bit more testing, but as of now, this is PD's lightest UC in terms of
painting requirements, and it demonstrates proper behavior in both the
IDE and when compiled (a rarity for me!).

The layer toolbox was my test bed, as it only has two labels but those
labels experience a lot of potential weirdness due to the layer being
resizable via click-dragging the left border.