This PR reduces the minimum lake line zoom to z3, allowing the largest lakes to show a renderable label. The lakeline function is restricted by the LineLabel() function, which limits lakelines to only those that are big enough to render a text label. Therefore, further restricting lakelines by zoom is not necessary.
* At zooms 9-13, water labels will now be rendered for water features that are at least 0.25 tiles in size. This means that water features that are the same size as a 128x128 pixel square will get a point label.
* Labels for large water features are now shown at the lowest zoom at which it's appropriate to show a label.
* Bay and strait names (`natural=bay` and `natural=strait`) are included.
* Large seas modeled as areas (e.g. Caspian Sea) render as `class=sea` rather than `class=lake`