astToStringastToString - Create an in-memory serialisation of an Object

Description:
This function returns a string holding a minimal textual serialisation of the supplied AST ObjectObject. The Object can re re-created from the serialisation using astFromStringastFromString.
Synopsis:
char $*$astToString( AstObject $*$this )
Parameters:
this
Pointer to the Object to be serialised.
Returned Value:
astToString()
Pointer to dynamically allocated memory holding the serialisation, or NULL if an error occurs. The pointer should be freed when no longer needed using astFreeastFree.