Version 1.9.1

Implemented TerminalProtocol for stoppark project.
Protocol specifics led to implementing slightly different
approach to TerminalPacketHeader (in contract to PacketHeader
from subway_protocol module). Since exact packet length is
unknown to us until whole packet has been transferred,
another method of asserting the end of transmission was used.
Filter class for terminal_protocol module - TerminalUnbytestaffer
performs end-of-packet check on input data and raises completed
flag when FEND byte appeared in transmission. After that, no more
data will be added to buffer, while its size can be treated
as a packet full size.

Reader and Protocol classes have been refactored to include
address (uint8_t addr) as first parameter in
send_command and send methods respectively.
Due to this change, all contactless reader API was fixed
to include zero address in their send_command calls.
This field has greater significance for terminal devices,
since we can communicate with more than one device in their network.

It's now possible to configure parity parameter for IOProvider
implementations.
(!)Current state of repository will compile correctly only on Win32,
since CP210XImpl had not been updated according to these changes yet.
Merge branch 'master' of https://github.com/stdk/u2