Throw exception early if manage channel returns a bad channel number.
Don’t mask out other bits in class byte.

Pass through secure messaging indication and command chaining control bits in class byte. The user must place them in the correct bits depending on channel number, though.
Make helper function pcsc_multi2jstring private.
Update comment for transmit to describe its behavior more specifically.
Explicitly require Java 1.7, since I already used AutoCloseable. See Issue 16.
Make JnaCardChannel implement AutoCloseable.