This change fixes looking up files that contain characters that may be

considered special in a URL, such as # or ?. There's a bit of a

backstory to this change.
Back in 2008, when the Subversion support was brand-new, we accepted a

patch that fixed looking up filenames containing spaces. Things with our

implementation was different back then, and this patch accomplished its

goals by taking a normalized URL to a file in Subversion, splitting the

path out, quoting its contents, and rebuilding the path.
The act of splitting the path resulted in # and ? characters being

split from the rest of the path, and they weren't put back in. This came

up in a bug report from Rob Petti, who provided a patch designed to work

around the bad behavior in the original implementation. After some

investigation, we figured out part of what was going on, and Rob built

an implementation that addresses the issue at its core, removing the

older code in the process.
This change builds on top of that, making some tweaks based on my

investigations into the original change, and Subversion compatibility.

It turns out that these days, we do not need to quote anything going

into Subversion paths (on either the PySVN or Subvertpy backends), but

as this was a problem at some point, we'll continue to quote for

compatibility.
Unit tests were added for both normalization and for lookup of files

containing spaces, &, #, and ? characters, using new files added

to our test repository.

Unit tests pass with both PySVN and Subvertpy backends.