Context now checks for bad shortnames being added to it.
added clarifying word to exception report.
Added test for spotting illegal shortnames to Context suite.
Another intermediate stage for basic auth.
Added elda:authFile to vocabulary.
(incompletely) revised code for basic auth configuration.
Same basic principle, but auth files are loaded from the standard path(set) in
AuthMap.USUAL_AUTH_PATHS which can be over-ridden in the config using elda:authFile
on the SPARQL endpoint.