Many changes to new login code based on Damien's feedback:

Many changes to new login code based on Damien's feedback:
- Removed many redundant accessor/mutator methods as they're not necesary
   in OpenSSH
- Added proper credits for OpenBSD code in loginrec.c
- Changed function definitions to the OpenBSD style
- Removed spurious 'L' prefix in line filename abbreviation for ut_line
- Added some documentation in loginrec.c
- Changed lastlog access function names
- Removed #include lines in mid-file loginrec.c
- loginrec.h, login.c and logintest.c changed to reflect new interface
- Added TODO note for ttyslot() replacement