Simplify linking against library in build directory

Make it easier to link against a shared library in the build directory
that has not been installed yet:

* Create all library symlinks in the build directory
* Set temporary install name with full path on Darwin
Regenerate charmonizer.c
Correct method calls in tests

Fix some cases where implementing functions were called directly.
Visibility of final methods

Implementing functions of final methods must be visible since they're
called directly.