Full support for deriving indexes on EMBEDDED docs & find_one_and_* methods.

0.8

The core wither crate is 100% backwards compatible with this release, but the Model trait has received a few additional methods. Namely the find_one_and_(delete|replace|update) methods. Came across a use case where I needed them and then realized that I never implemented them. Now they are here. Woot woot!

The wither_derive crate has received a few backwards incompatible changes. The motivation behind doing this is detailed in #21. The main issue is that we need the derive system to be abstract enough to deal with embedded documents. The backwards incompatible changes are here.

• within #[model(index())], the index_type attr has been reduced to simply be index. All of the same rules apply as before. This change was made for ergonomic reasons. Less typing. Easier to follow.
• within #[model(index())], the with(...) attr has been updated to support subdocuments. The new syntax for this attr is with(field="...", index="..."). Supply a with(...) attr for each independent field to include.
• within #[model(index())], the weights(...) attr has been updated for the same reason as with. Now, you need to supply one weight(field="...", weight="...") per field weight you are specifying.

The only net-new item being added here is that now, within #[model(index())], you can use the attr embedded="..." to cause the index declaration to apply to the embedded document/field specified. See the docs for more details.

It is my sincere hope that this is the last breaking change I will need to make to this crate before promoting this crate to a 1.0.0 release. Let's hope! Please let me know if there are any issues you have with these updates.