highlighted map squares shown offset

[japonicus]

The map square marker is misaligned with the grid.

[japonicus]

I've inadvertently been building against a more recent of the geodesy library, where OsGridRef.parse() always returns metre precision co-ordinates, i.e.

OsGridRef.parse('SD59') OsGridRef {easting: 350000, northing: 490000}

whereas the version you've built against returns

OsGridRef.parse('SD59') OsGridRef {easting: 35, northing: 49}

This means that no offset applied, so the grid-square is offset SW by half the square length.

Will patch this so that either library works.

[japonicus]

closed by #19