Move `todo.md` contents into separate issues

todo.md

@@ -1,32 +0,0 @@
-# TODO
-
-- Make it easy to extend and add custom predicates
-
-- Parse out the input string literal when possible to create good error messages:
-
-```js
-// Before
-ow(obj.foo, ow.string);
-// ArgumentError: Expected argument to be of type `string` but received type `null`
-
-// After
-ow(obj.foo, ow.string);
-// ArgumentError: Expected argument `obj.foo` to be of type `string` but received type `null`
-```
-
-- Ability to reuse validations:
-
-```js
-const checkUsername = ow.create(ow.string.minLength(4));
-checkUsername(username);
-```
-
-- At some point would be nice to parse the source on error and show the error pointing to the source. Using https://www.npmjs.com/package/babel-code-frame
-
-- Ability to use custom assertions. Should be very easy to create. We can't bundle it all.
-
-
----
-
-
-Feedback from Sam: https://gist.github.com/SamVerschueren/6e1c7e9f3183dbe1b7d8909c6ff07337