Adding Ryser, 2014b.
Update Cournoyer, 2014.
Allow per-subdomain SCALAR variable support
Clarify documentation comments
Assert old SCALAR dof requests are appropriate

I doubt anyone will repeat the bug I just fixed, but if they do let's
try to do a better job of catching it.
Merge branch 'sparse_scalars'

Squashed some bugfix commits and fixed some whitespace errors.

See also #341.
Allow the user to limit point locator searches to subsets of the mesh.

We have an application where a requested point lives on the interface between subdomains, and it is desirable to restrict which subdomain the returned element belongs to. This commit implements this feature, with backwards compatibility through the API using default function arguments.