0.2.0

Added

• Support for accessing global variables with CFFILibraryHandle.get_global
• CFFIType.alloc_array to allocate an array of values
• CFFIPointer.duplicate_array to duplicate more than one element from a pointer as an CFFIOwnedValue
• CFFIPointer.get_address method to get the base address of a pointer.
  Useful to compare pointers by value.
• Support for passing CFFIFunctions as function pointers to struct fields or native function arguments.
• Add CFFICallableFunction class that wraps Callable as native function pointers using libffi's closure API.
  They can be created using CFFIScope.create_function.
• Support for passing any packed array (other than PackedStringArray) as pointer to native functions.
• CFFIPointer.to_*_array methods for copying data from pointers as other types of packed arrays
• StreamPeerCFFIPointer stream peer that handles a binary data stream from a CFFIPointer.