Release 4.3.0

### Summary:
This release is the first supported release of the stdlib 4 series. It
emains backwards-compatible with the stdlib 3 series. It adds two new
unctions, one bugfix, and many testin

#### Features:
- New `bool2str()` function
- New `camalcase()` function

#### Bugfixes:
- Fix `has_interface_with()` when interfaces fact is nil