Definition of the OCL Helper API for syntax completion support and a simplified parsing model for embedded OCL constraints and expressions.

## Package Specification

The primary interface in this package is the {@link org.eclipse.ocl.helper.OCLHelper}, which provides OCL syntax completion assistance and parsing support. Instances are obtained from the {@link org.eclipse.ocl.OCL} class.

OCL code completion suggestions are represented as {@link org.eclipse.ocl.helper.Choice}s, which indicate the name of a language construct, a description, and the {@linkplain org.eclipse.ocl.helper.ChoiceKind kind} of construct.

The `OCLHelper` also provides a simple API for parsing constraints and expressions embedded in models:

- invariants and additional attribute/operation definitions in a classifier context
- pre/post conditions and body conditions in an operation context
- initial- and derived-value expressions in an attribute context

The helper also supports the simultaneous definition and value binding of "global" variables, to support injection of custom variables into OCL expressions.