Compile sources with debug information.
Add a new target "lint" that runs lint on the source code for both the
FreeBSD and Linux case.
Let the install target depend on the final binaries (mostly a safety guard).
Fixes after running 'make lint'
Fix indices for the civil warning buffer in the comments.
- Start decoding when either an end-of-minute marker is received or
  this minute is too long (overflow).
- Denote an overflow with an 'L' instead of a '>' sign for clarity with
  the '>' sign shown if DT_LONG is true.
Remove a trailing tab, and spell "Sunday" correctly.
Clear olderr when it was active but this minute is ok, independent of
any DST change.
Style catch-up.
Better explain why we save the GETBIT_TOOLONG flag at the start of get_bit().
Also show the bit position and the state when displaying verbosely.
Fix a buffer overflow of the buffer variable (here into the state variable)
that would happen if bitpos == sizeof(buffer)-1 . In the old situation,
the bit position was checked before incrementing it instead of checking it
afterwards, leaving an opportunity for incrementing it to sizeof(buffer).
The code in get_bit() would then store the current bit value at this
illegal position.

While here:
- do not set GETBIT_EOM when the buffer overflows (behaviour is preserved
  in dcf77pi.c)
- reset GETBIT_TOOLONG immediately after resetting the bitpos variable
  instead of keeping it set until the next end-of-minute marker.
Another style catch-up.