Effects > Artistic > Stained Glass: clean up UI
pdPackager: fix buffer size calculation when zLib is in use
Preferences: add support for Undo/Redo data compression

It might seem counterintuitive, but disk latency is generally less
expensive than on-the-fly compression of large data sets (e.g. bitmap
data).  For this reason, PD has traditionally used uncompressed data for
its Undo/Redo buffers, as free file space is cheap and this is an easy
way to boost performance.

As part of my new Performance initiative, however, it was a good time to
finally expose this behavior to the user.  PD now supports variable
compression of Undo/Redo data, as set via the Options > Performance tab.
Increasing compression levels is an easy way to trade performance for
buffer file size, which will be a good trade-off for some users.
Slider/text UC: increase tooltip display time

This brings it into line with other tooltip delay times across the
program.