Alternate bike network rendering ideas

Some ideas for revisiting Ungap the Map cartography.

1) Don't draw roads unsuitable for cycling at all, or draw them extremely de-emphasized. The big important routes should be thick and obvious. Judge small residential streets based on the shortcut calculation from the LTN tool.

2) https://www.cincymap.org/cbm/, described at https://cartographicperspectives.org/index.php/journal/article/view/cp81-wessel-widener/1414. There are so many awesome ideas here I don't even