Fix a bug in function DoFCellAccessor::distribute_local_to_global()

[YiminJin]

I found a bug in line 2960 of file include/deal.II/dofs/dof_accessor.templates.h. The bug is caused by passing boost::container::small_vector<>::iterator to function SparseMatrix<>::add(), which only takes a C pointer as the third argument. I simply replace dof_indices.begin() by dof_indices.data() (as in old versions of deal.II).

[drwells]

Thanks for the fix! Would you be willing to do two more small things:

1. rebase so you are down to one commit (we try to avoid adding extra merge commits into our history)
2. add a short test which calls this function

[YiminJin]

I have rebased the branch. It is the first time I use the "rebase" command so I don't know if I have done it right. Please let me know if there is something wrong.

A short test (test.txt) is appended to this comment.
test.txt

[marcfehling]

A short test (test.txt) is appended to this comment.
test.txt

Would you include your test to the testsuite? You can find more information about it here:
https://www.dealii.org/developer/developers/testsuite.html#layoutaddtests

I suspect the right subfolder for the test would be tests/dofs among the dof_accessor tests. There you can also have a look at how other tests work. Please let us know if you need help with that.