[CppAD] Recent bug fixes

[Brad Bell]

In December of 2016 I reorganized the source code that optimizes CppAD 
function objects; i.e.,
     https://www.coin-or.org/CppAD/Doc/optimize.xml
While this made the code much easier to understand, there were some bugs 
introduced in the optimization of conditional expressions; see the 
heading 04-02 and 03-25 on
     https://www.coin-or.org/CppAD/Doc/whats_new_17.xml

In addition, I recently fixed some valgrind errrors that were not errors 
in the CppAD, but make it easier to use with valgrind; see the heading 
03-29 on the whats new page above.

These fixes have also been implemented in the 20170000.4 release; see
     https://github.com/coin-or/CppAD/releases
or
     https://projects.coin-or.org/CppAD/browser/releases