check resolve_tpye in inspect function (#51)

[src] fix various warnings

[function-call] get_entry_point_for_fn: implement

[lang] add a tree type that represents an FFI closure

[evaluate] fix iteration over fn args in eval_fn_call

[testsuite] default-arg-promotions: new

[function-call] respect the 'default argument promotions'

[evaluate] make 'make_live_var' non-static

[function-call] only pass ret ptr if lv non-null

[evaluate] make sizeof() return an appropriately sized LV

[testcase] fix printf_double_live_var

[evaluate] implement ffi fncalling for function pointers

[evalute] remove unused funvtion `make_fncall_result'

[makefile] include 'ffi-types.h' in ths sources list

[function-call] implement function return values