Add support for 'short' and 'byte' types
Recognise 'array' in dictionary (but don't use it)
Recognise (but don't support) tlv
Add support for 'signed'
Frig for format=1,1,c
Recognise (but don't support) combo-ip
Merge branch 'candlerb/shortbyte' of https://github.com/candlerb/pyrad
Add ipv6prefix support, improve dictionary parsing

- Add support for ipv6prefix datatype (requires ipaddress module)
- Add datatype integer64
- Add test data for short and integer64
Add partial support for tunnel tags (RFC 2865).