Dependency on pyserial is removed. Because pyserial v3.5 is not backward compatible on some exceptions, some imports were broken. Actually usbserial4a does not really depend on pyserial. It just needs a compatible class interface.
0.2.0
FTDI serial driver - done and tested with FT230X. CDC ACM serial driver - done and tested with MCP2200. CP210x serial driver - done and tested with CP2102. CH34x serial driver - done and tested with CH340. PL2303 serial driver - done and tested with PL2303.