templater: consistently join() string-like object per character (BC) The old behavior was copied from join() of a lazy generator string, which was unified to the behavior of join() of a byte string by the previous patch. This patch fixes the mappable type to do the same.

templater: always join() over a wrapped object (BC) This is a behavior change in a sense that join() of a byte string is no longer "implementation dependent." Before, if a byte string was backed by a lazy generator, join() would concatenate each chunk with the specified separator, which seems wrong. The new behavior is always join() each byte. TypeError on join() over uniterable is also fixed.

templater: add wrapped types for pure non-list/dict values These wrapper types will allow us to get rid of some isinstance() business. A bytes object needs to support sequence-like operations (e.g. join(), ifcontains(), etc.) That's why we have two wrapper classes. Tests will be added later.

templater: unify unwrapvalue() with _unwrapvalue() All weird generators got removed from the hgweb codebase. We still have inconsistent behavior regarding join() of a byte string, which will be addressed later.