For 10 years (commit e212e2c5), sbbs_t/console.getstr() has limited length
of string input to the available columns of the terminal.

To fix issue #869, rather than change getstr()'s default behavior, add a new
mode flag: K_LINEWRAP which does not limit the string length input based on
the terminal width (and the current column) (e.g. for use with ;string
commands from the default command shell).

Ideally, I'd like to have a marquee-style option (K_mode flag) where longer
strings just side-scroll to accommodate strings longer than the terminal
width, but in the mean-time, this'll do.

So anywhere we think a narrow (e.g. 40 column) terminal is being excessively
restricted in string input width and starting the input in the first column
is not an option/solution, adding the K_LINEWRAP flag to the getstr() call is
the proposed solution.