Alias Tcflag to UInt64 instead of UInt32

This is probably system dependent but UInt64
should work on more systems until we can parse
header files
Ignore EAGAIN in read_nonblock

Instead just return what we could successfully read
Also adapt 2048 samples read_keypress to the new behaviour
Merge pull request #186 from jhass/2048_fixes

2048 fixes (close #184)