FixedWindowRoller is unreliable under Linux and Windows

[Coding-Badly]

Background

This is a potential solution for issue #213.

Linux and Windows file systems allow illegal Unicode sequences for directory names and file names. The Rust folk provide OsStr and OsString for dealing with the problem.

Currently, log4rs uses Rust strings for directory names and file names which makes it troublesome to use when an illegal Unicode sequence is involved.

The R&D repository for this work is available here. It includes an example that creates folders with an illegal Unicode sequence under Linux and Windows.

Change

This pull request introduces PatternPathBuf. Essentially it's a PathBuf with support for safely replacing {} eye-catchers.

[estk]

@Coding-Badly This change makes sense, there are a few other breaking changes that I'd like to make so maybe we'll keep this open for a bit while we proceed towards 2.0?

[Coding-Badly]

...a few other breaking changes...

If this is a breaking change then I made a mistake. 😄

...maybe we'll keep this open for a bit while we proceed towards 2.0?

I'm good with that.