new abstraction layer open_file_description added to filesystems, related to issue #78
pread, pwrite info added into status file
pread,pwrite offset fixed for InMemoryFs
dup/dup2 code pieces added
tests for pread, pwrite and dup added
fixed dup entry point
dup test updated, added inMemoryFs test
Devices fs right offset handling
fixed getdents for Devices fs
old dup impl removed from Devices FS. dup, dup2 generic implementations added into transprent_mount, dup2 test added
Modified dup function definition in ZRT public interface
Merge pull request #88 from YaroslavLitvinov/issue78

Issue78