Added a missing CPDate.j import in CPExpression_function that was causing an 'unknown variable CPDate' error in deploy builds.
Added documentation for +expressionForSubquery:...
Added licence headers with credits.
"($)path.($)variable"
"SUBQUERY(collection, $x,$x = 2)"
"sum:(arg1, ...)"
"FUNCTION(target, selector, arg1, ...)
"object[expression]"
"set UNION|INTERSECT|MINUS otherset"
Fixed a bug where CPExpression_set was evaluating to an expression instead of a set.
Replaced parsing exceptions with a generic function indicating where it failed.
Added missing getters in CPExpression.
Added a type: argument to FunctionExpression initializer used by subclasses to init super with their own type.
Fixed evaluation with bindings dictionary in CPExpression_variable. Allow values in bindings to be a constant or an expression (per cocoa).
Tests: added tests for subqueryExpressions, for variableExpression evaluation where the value in the bindings dictionary can be either a constant or another expression.
Parsing a simple variable expression works (e.g. '$x = 12'), parsing a variable in a combined path (e.g.
'$x.path = 12' won't yet.