Get rid of EIGEN_TEST_FUNC, unit tests must now be declared with EIGEN_DECLARE_TEST(mytest) { /* code */ }.

This provide several advantages:
- more flexibility in designing unit tests
- unit tests can be glued to speed up compilation
- unit tests are compiled with same predefined macros, which is a requirement for zapcc

test/geo_orthomethods.cpp

@@ -115,7 +115,7 @@ template<typename Scalar, int Size> void orthomethods(int size=Size)
   VERIFY_IS_APPROX(mcrossN3.row(i), matN3.row(i).cross(vec3));
 }
 
-void test_geo_orthomethods()
+EIGEN_DECLARE_TEST(geo_orthomethods)
 {
   for(int i = 0; i < g_repeat; i++) {
     CALL_SUBTEST_1( orthomethods_3<float>() );