Merge pull request #4 from jaydchan/owl_data-fix

Updated span macro st it now recognizes the <= operator
Whitespace correction.
Merge branch 'master' of github.com:phillord/tawny-owl
Whitespace changes.
All functions now carry documentation.
Was incorrectly producing embedded lists for Restrictions.
Some implementation also moved from backtick.
Made partitioning function of groupify generic.
Improved error reporting of groupify.
Characteristics of properties are now specified by keywords
rather than vars resolving to functions.
Default ontology was being mistakenly used in guess functions.
dataproperties also use keywords now.
Inclusive and exclusive were the wrong way around.
Reworked literal support.
Tests for groupify-at
Default ontology checks restored.
New Tests for datatypes.
Documentation update. Pointless call to toURL removed.
New issue on datatypes
Bump to snapshot version due to change in OWL2Datatype.
Built-in datatypes now specified using keywords.
Changes to render.clj to cope. Lots of tests changed syntax
and some new ones added.
Initial checkin
Annotation now takes a literal or a string and interprets it correctly.
Rendering of annotation was broken anyway, and has now been updated to
render using an explicit literal, regardless of the datatype.