fix AFCFileRef[Read|Write] prototypes

Incorrect AFCFileRefRead prototype was causing crashes in 64-bit build when reading large files.
handle no --args

When no --args are passed application was started with {args} as argument instead of no argument.
Fix usage semantic and pair of resource leaks

AFCConnectionOpen and AFCFIleInfoOpen don't require initialized pointer to pointer to result, but do require corresponding Close calls.
arrange callback in read_dir for future use

Custom callback is called for every file or directory listed on device. This will be used for file download.
Merge pull request #66 from dot-asm/master

Fix AFCFileRef[Read|Write] prototypes