Lift the 1024-character limit on configuration file lines.

Lift the 1024-character limit on configuration file lines.
To do this, I changed the configuration parser so that instead of reading
the line into a buffer and munging it in-place, it builds a string
containing the current line (via successive getline() calls) and then
walks down that string.  Instead of skipping comments and whitespace by
erasing them from the buffer, the new code just skips over them.