Fix stan::math::exp behaviour for NaN (for matrices of doubles)
Using iterators instead (in stan::math::exp)
updating exp to call the unqualified one, which should be stan::agrad::exp
stan::math::exp(Eigen::Matrix) will have an specialized version for double that will check for nan inputs
even simpler and better solution
just removed redefined 'unlikely' macro
added NaN test for exp
Remove unused add method accepting vectors

This function is no longer used by PyStan and it is, moreover, designed
incorrectly. In RStan and PyStan chains are effectively stored in "row order" as
each parameter has its own vector<double> of size `num_iter`. This function
assumes this arrangement is transposed, that one has has `num_iter` vectors.
removing compiled manual from the repository
Merge pull request #1021 from stan-dev/feature/remove-manual-2.4.0

removing compiled manual from the repository
moved likely and unlikely macros to their own header files
updating definitions of macros likely and unlikely
Merge pull request #1020 from ariddell/feature/remove-chains-add-method

Remove unused add method accepting vectors
Merge pull request #1018 from stan-dev/feature/issue-1002-unlikely-macro-redefined

Remove warning for 'unlikely' macro redefinition
Revert "Merge pull request #1020 from ariddell/feature/remove-chains-add-method"

This reverts commit 8820ac2e7b4b239b46f3e2c6048b8a3d11ef3404, reversing
changes made to 575deeed77ef3bef9aff85b9d5da51f2bb2afed8.
doxygen: removing checked in artifacts
doxygen: adding amsmath as an extra latex package
doc: moved int_step documentation
doc: moved min and max documentation
added fitemnobody for items without a body