no longer requires pysendfile third party dep (it was Python 2.7 only)
bump up pyftpdlib version to 2.0.0 since we're breaking compatibility
get rid of appveyor CI, which was used to test python 2.7 on Windows
removes around 700 LOC
Some re-implementation notes:
unicode wasn't really handled properly (it's impossible on python 2.7); got rid of many str.decode("utf8") and unicode(path, 'utf8', 'ignore') conversions etc.
use OSError instead of EnvironmentError, IOError, WindowsError, select.error, socket.error
replace EEXIST, ENOENT, etc. with FileExistsError, FileNotFoundError, etc.
Some re-implementation notes:
str.decode("utf8")andunicode(path, 'utf8', 'ignore')conversions etc.OSErrorinstead ofEnvironmentError,IOError,WindowsError,select.error,socket.errorEEXIST,ENOENT, etc. withFileExistsError,FileNotFoundError, etc.