playing with scanlines

Experimentation with pushing vectors into a simple, json parsable hitgrid, using modified AGG algorithms.

A step toward:

https://github.com/mapbox/mbtiles-spec/blob/master/1.1/utfgrid.md

To test do:

make; ./run

You should see something like:

    { "grid":
    [
    "                                                                ",
    "                                                                ",
    "                                                                ",
    "                                                                ",
    "                                                                ",
    "                                                                ",
    "                                                                ",
    "                                                                ",
    "                                                                ",
    "                                                                ",
    "                                                                ",
    "                                                                ",
    "                                                                ",
    "             bbbbbbbbbbbb    ccc                                ",
    "             bbbbbbbbbbbb   ccccc                               ",
    "             bbbbbbbbbbbb   ccccc                               ",
    "      aa     bbbbbbbbbbbb  ccccccc                              ",
    "      aaaa   bbbbbbbbbbbb  ccccccc                              ",
    "     aaaaaaa bbbbbbbbbbbb  ccccccc                              ",
    "     aaaaaaaabbbbbbbbbbbb cccccccc                              ",
    "     aaaaaaaabbbbbbbbbbbb ccccccccc                             ",
    "       aaaaaabbbbbbbbbbbb ccccccccc                             ",
    "         aaaabbbbbbbbbbbb ccccccccc                             ",
    "           aabbbbbbbbbbbb ccccccccc                             ",
    "             bbbbbbbbbbbb ccccccccc                             ",
    "               aaaaaaaaaacccccccccc                             ",
    "                 aaaaaaaacccccccccc                             ",
    "                   aaaaaacccccccccc                             ",
    "                     aaaacccccccccc                             ",
    "                       aacccccccccc                             ",
    "                         cccccccccc                             ",
    "                         cccccccccc                             ",
    "                         cccccccccc                             ",
    "                         cccccccccc                             ",
    "                         cccccccccc                             ",
    "                         cccccccccc                             ",
    "                          ccccccccc                             ",
    "                          ccccccccc                             ",
    "                          ccccccccc                             ",
    "                          ccccccccc                             ",
    "                          ccccccccc                             ",
    "                          cccccccc                              ",
    "                           ccccccc                              ",
    "                           ccccccc                              ",
    "                           cccccc                               ",
    "                            ccccc                               ",
    "                            ccccc                               ",
    "                             ccc                                ",
    "                                                                ",
    "                                                                ",
    "                                                  dddddddddddddd",
    "                                                  dddddddddddddd",
    "                                                  dddddddddddddd",
    "                                                  dddddddddddddd",
    "                                                  dddddddddddddd",
    "                                                  dddddddddddddd",
    "                                                  dddddddddddddd",
    "                                                  dddddddddddddd",
    "                                                  dddddddddddddd",
    "                                                  dddddddddddddd",
    "                                                  dddddddddddddd",
    "                                                  dddddddddddddd",
    "                                                  dddddddddddddd",
    "                                                  dddddddddddddd",
    ]
    }