Add support for displaying cardinal directions instead of headings.

[tmiw]

Resolves #682 by adding a new setting in Tools->Options to show directions (e.g. N/S/E/W) instead of degrees for the Heading/Direction column.

[barjac]

Great!
Just one thing, since the headings in cardinal mode are text, should they not be left justified to use the same convention as other columns?

[tmiw]

Great! Just one thing, since the headings in cardinal mode are text, should they not be left justified to use the same convention as other columns?

Updated.

[barjac]

Perfect!