N3960 additional algorithms implemented

A number of new algorithms have been implemented in N3960, and should be ready to merge into master. These include:

* `find`
* `find_if`
* `find_if_not`
* `find_end`
* `generate`
* `generate_n`
* `mismatch_binary`
* `mismatch`

Internal changes were made to the structure of the partition as well.