Issue 29 - Either get rid of getVariableData or introduce a hint annotation

If we don't decide to ban the ability to specify non-static strings as the
arguments to getVariableData and related functions then we need to introduce
an attribute that can be applied to variables as a 'hint' that these
variables should be persisted for compensation purposes. We will also have
to introduce a new fault if, at runtime, an attempt is made to access a
variable that wasn't marked for persistence.

	Thanks,
		Yaron