Garbage collection for info-ffi
Update README.md
Merge pull request #26 from hying-caritas/gc

Garbage collection for info-ffi
struct.lisp: Add struct :free special method

To free struct allocated via :allocate special constructor.
gir-test.lisp: Add test case for struct :free
Merge pull request #28 from hying-caritas/struct-free

struct.lisp: Add struct :free special method
function.lisp: Move some operation to build time

Move return value translator creating.
function.lisp: Add return value clear support

Based on whether caller owns the return value.
function.lisp: Use with-foreign-objects to manage giargs
function.lisp: Add garbage collection support for "out" object

Return value or out argument.
Merge pull request #29 from hying-caritas/return-proc

Return value clear and GC