Allow line files to be used for border creation

We should add a feature in border editor that will allow LNW files to be referenced for border creation. So for instance if there is a center line we can select the line and then say create border that is 100m left and 100m right of center and then add the top and bottom of the border to be selected biased on the station. So you would select say station 100 for the top and then say 50m above or below station, and the same for the bottom, Additionally have the ability to lock one of the dimensions and then drag the top and bottom to where you need, like a matrix. Needed because some surveys and dredge operations have out of bounds areas that are based on a distance from a center line or other reference.