Add a 'local' file location for tests

This is the first step required to allow for unpacking l3kernel and having
files from this selected 'locally' without needing to install to TEXMFHOME.
While running the test program from 'here' and using -output-directory looks
a bit odd, it means that the relative paths for everything are straight-forward
as they all work using maindir.


git-svn-id: http://www.latex-project.org/svnroot/experimental/trunk@4789 de43f980-851b-0410-b2f7-c40aca1f87e0
Add setting of TEXINPUTS to building doc

This will make more sense once l3kernel unpacks into the local location.


git-svn-id: http://www.latex-project.org/svnroot/experimental/trunk@4790 de43f980-851b-0410-b2f7-c40aca1f87e0