Fix most Doxygen warnings. Also add links to stable documentation from unsupported modules (by using the corresponding Doxytags file).
Manually grafted from d107a371c61b764c73fd1570b1f3ed1c6400dd7e

diff --git a/doc/CoeffwiseMathFunctionsTable.dox b/doc/CoeffwiseMathFunctionsTable.dox
index c39a4bf..12a565b 100644
--- a/doc/CoeffwiseMathFunctionsTable.dox
+++ b/doc/CoeffwiseMathFunctionsTable.dox
@@ -63,7 +63,7 @@
   \anchor cwisetable_conj
   a.\link ArrayBase::conjugate conjugate\endlink(); \n
   \link Eigen::conj conj\endlink(a); \n
-  m.\link MatrixBase::conjugate conjugate();
+  m.\link MatrixBase::conjugate conjugate\endlink();
   </td>
   <td><a href="https://en.wikipedia.org/wiki/Complex_conjugate">complex conjugate</a> (\f$ \bar{a_i} \f$),\n
   no-op for real </td>
@@ -133,8 +133,9 @@
   <td class="code">
   \anchor cwisetable_pow
   a.\link ArrayBase::pow pow\endlink(b); \n
-  \link Eigen::pow pow\endlink(a,b);
+  \link ArrayBase::pow(const Eigen::ArrayBase< Derived > &x, const Eigen::ArrayBase< ExponentDerived > &exponents) pow\endlink(a,b);
   </td>
+  <!-- For some reason Doxygen thinks that pow is in ArrayBase namespace -->
   <td>raises a number to the given power (\f$ a_i ^ {b_i} \f$) \n \c a and \c b can be either an array or scalar.</td>
   <td class="code">
   using <a href="http://en.cppreference.com/w/cpp/numeric/math/pow">std::pow</a>; \n