added Column Definition examples
fix definition error
start non conditional expressions
begin adding expressions
start adding in allt he single expressions
add UTF-8 ref to bibliography section
further work on single expressions
various column expression updates
finish single expressions in body
begin adding ebnf to appendix too
more EBNF
finish updates to ENF appendix for single expressions
exertnal single expressions and corrections
finish single expressions and helpers
bring ebnf appendix into line with body
add combinatorial and parenthesized expressions
finish column validation sections
started to add data types
finish main body draft
finish ebnf appendix