Instruct guard to ignore hidden files

Changes to files where the name starts with a dot should not cause a
rebuild.  Doing so causes pointless rebuilds every time vim updates its
swap file.
Have SVG image use entire space allocated for it

Allow web page to determine how much space is used for the map, and have
the SVG scaled to fill that space other than a small amount of padding.
Comments in .editorconfig should be on own line

Since I initially created the .editorconfig file the format description
has been clarified to say that comments need to be on separate lines,
modify to comply with that change.
Refactor selecting of counties

Create a function to select a county from the map rather than
duplicating code.
Don't notify of successful builds

The way guard notifications are showing up for me currently is really
annoying, so don't notify of successful builds.
Make map larger

Eventually I want to base the size of the map on the window size, but
for now just set a decent size for my use.
Prevent making new selection after correct answer

Once the correct region has been selected (either by clicking it or
using the reveal answer button) prevent further attempts.