wxSpinCtrlDouble only updates its value when the spin button is clicked
or it loses focus, and in some cases we want to read the value while it
still has focus.

Closes #1610.

Always store the actual zoom level, rather than sometimes the zoom level
and sometimes the slider position.

Updates #1597.

For some reason horizontal scroll comes pre-flipped.

The standard controls aren't particularly usable, but the OS X
implementation of wxDVC doesn't actually support custom renderers and
not very usable is mildly better than entirely nonfunctional.

'isComment ? "" : actor' results in actor decaying to a const char * in
the local charset rather than converting "" to wxString, which breaks
things when unicode is involved.

Creating an indexer can fail for reasons other than the file not
existing. This check is still not completely correct, since FFMS2 uses
the wrong error codes in a bunch of places.

Move the generic lua check to after the checks for lua 5.1 and check for
lua < 5.2.

Closes #1559.

It would be nice if this didn't require adding it in five different places...

With wxWidgets trunk keydown events are no longer generated for
Ctrl-C/X/V on Windows, which breaks the custom copy/paste handling.

There were two checks for reads past the end rather than checks for
before start and after end.

Closes #1556.

Strings in Matroska files are all either UTF-8 or a UTF-8 subset, not
whatever the current locale happens to be.

The conversion to ASS was creating invalid lines which could not be
parsed, resulting in the worker thread crashing.

Closes #1554.

At very large and very small sizes, setting the window's size with
SetSize may not actually result in the window changing to the requested
size.  Once this happened future adjustments to the size were incorrect,
and the video display would sometimes not fit in the window, and on os x
the window could get set to a negative size, with weird results.