[Ipopt] Ipopt release 3.13.0

[Stefan Vigerske]

Hi,

Ipopt release 3.13.0 is available.
It is essentially unchanged from the 3.13 beta that was announced a 
month ago. Thanks to everyone who gave it a try.

This release comes with a larger renovation of the build system and a 
changed directory structure (eliminated the top directory), which is the 
result of a long and still on-going effort to use recent autotools 
versions for various COIN-OR projects, reduce future maintenance 
efforts, and adapting behaviors of standard autotools-based projects.
As a consequence, a monolithic build of Ipopt, which builds Ipopt with 
all its dependencies in one run of configure and make is no longer 
possible. Dependencies should now be build and installed before building 
Ipopt.
Additionally, support for some outdated versions of dependencies and 
unmaintained components of Ipopt have been dropped and some improvements 
that may require changes on the users side have been applied.
A more detailed list of changes can be found in Ipopt's changelog:
https://coin-or.github.io/Ipopt/CHANGELOG.html

Updated installation instructions are also found in the documentation:
https://coin-or.github.io/Ipopt/INSTALL.html

Enjoy,
Stefan