support 'ansi-bbs' and 'ansi' (syncTerm).

Note CHANGES addition regarding the meaning of the
'termcap-ansi' value. It now transliterates both
ways (by using "startswith" instead of ==).

also, rename sense.ans for encoding.ans for later
charset.py update.
charset.py for the new style.

Do a better job about the utf8/vga font encoding
selection on-connect (I think beardy or hellbeard
has to actually chose ! encoding to make utf8
work on their terminal client, gnome?)
better ansi/cp437/encoding selection on-connect
TTYPE_UNDETECTED identifier. socket_recv returns N

where n is number of bytes received. can be used
for shorthand "get some bytes, and if i got some,
read them" for "if socket_recv(): ..."

other various doctoring updates.
a few pep8's, change 'import' to '__import__'

for modules imported purely for their side-effects
this differentiates them from the other bastards.
fix: add 'anoncmds' to default.ini

was missing, so even if anonymous is enabled,
there are no allowable anonymous nicks to login
as over ssh or rlogin.
engine.py cleanup and refactor

finer logging
use warnings instead of manual stderr.write
use .format over old-style % formatting
document and explicitly expect env['encoding']
common.py: add vertical_padding option to banner
nua.py: fix for bleeding of term.reverse
matrix.py: docstring fixes
move on-connect user verify functions to userbase

check_new_user, check_bye_user, etc. previously
authored for ssh protocol can now be shared by
other protocols (rlogin, for example); moved to
userbase.py
bugfix userland telnet

was missing SEND constant (thanks flake8)
rlogin love

- add missing 'kind' attribute ('rlogin')
- remove unused recv MSG_OOB data
- refactor ConnectRLogin (mccabe complexity)
- also handles on-connect data negotiation better
- detects BSD vs. SyncTERM, sets encoding
- supports new@, anonymous@ login
- better logging
telnet love

- SB_MAXLEN belongs only in telnet,
- socket_recv() should return 0 on EWOULDBLOCK
- re-use BaseClient TTYPE_UNDETECTED attribute
- document negotiation parameters
- move negotiation from banner() to run()
- improved error logging
ssh love: host key config value now optional
msgbase: remove duped DBProxy import