ipopt include folder changed recently

[Moisan]

Bug Report

• I checked the documentation and the forum but found no answer.
• I checked to make sure that this issue has not already been filed.

Environment

• DART version: 6.9.4
• OS name and version name(or number): macOS Catalina
• Compiler name and version number: Clang 3.9.1

Expected Behavior

dartsim should be able to compile with the latest ipopt version (currently 3.13.2).

Current Behavior

/tmp/dartsim-20200921-64782-nd7k16/dart-6.9.4/dart/optimizer/ipopt/IpoptSolver.hpp:36:10: fatal error: 'coin/IpTNLP.hpp' file not found
#include <coin/IpTNLP.hpp>
         ^~~~~~~~~~~~~~~~~

Steps to Reproduce

1. install ipopt 3.13.2
2. build dartsim 6.9.4 with this version of ipopt

I believe the issue is coming from a change of directory for the include files from ipopt between version 3.12 and 3.13. To fix this issue, one can change the include line to #include <IpTNLP.hpp>. However this would make dartsim not backward-compatible with previous versions of ipopt.

Note that there is another problematic include in optimizer/ipopt/IpoptSolver.hpp that will also need to be changed: #include <coin/IpIpoptApplication.hpp>.

[jslee02]

Thanks for the report! This should be fixed by #1506