move Html_Browser into jes.gui.components and simplify JESUI

Html_Browser is now named HTMLBrowser (as is intended for classes) and
lives in jes.gui.components.htmlbrowser. It's exactly the same.
However, JESUI's usage of a Html_Browser_With_Hide class was removed,
as it turned out to be completely unnecessary and to make the program
longer.
move JESTabnanny into jes.util

This was changed as much as Html_Browser (i.e., not at all).
fix configuration dialog's refusal to close

Because I had forgotten to import Pixel, the settings window couldn't
set the wraparound preference on Pixel when it closed. So, I added
the import, and now it's fine.