Draft changes to the way map searches work, fixing bugs and adding features (such as site markers).
Added documentation comment to index method.
Added and set instance variables needed for dealing with map markers.
Added code to update the map markers according to the search results if the map is showing.
Included serialization module so we can output rows as hashes.
Made marker array global so AJAX code can access it.
Index markers by site_id.
Cleaned up code.
Changed default marker color to white.
Added code to color markers in search result red.
Added hidden form variables to save state -- whether the map is being displayed, and whether we are searching by site or by region.
Base the test of whether we should restrict search results by location on the 'mapDisplayed' parameter.
Corrected name of searchingBySite parameter.
Handle setting of "mapDisplayed" parameter in the map-display toggle function.
When we toggle map display on, update search results based on remembered parameter values.
Don't erase search area overlay and don't "forget" map zoom and center when we toggle display off.
Toggle map display on when page is reloaded with mapDisplayed set to "true".
Handle setting of the "searchingBySite" parameter.
Replace 'searchingBySite' with 'mapSearchMode', which has three
possible values: "by site", "by region", and "off".  Added code to
handle "remove_map_location_filter", which sets mapSearchMode to
"off", updates the search results (and map markers) and removes the
overlay (if any).
Make control structure tests depend solely on the mapSearchMode parameter.
Replaced "searchBySite" form parameter by "mapSearchMode".
Turn off map location restriction on search results when map is hidden, not just when mapSearchMode == "off", so that we can remember mapSearchMode when we turn map display back on.
Add code to show or hide the "Remove Map Location Restriction" button according to whether the map is showing or hidden.
Code updates to show map sites within search region that are not selected by search terms (in yellow).
Added legend to map.
Added "Remove Map Location Restriction" button, changed map width to 100% of container, and added (temporarily) a style element for the map legend.
Copied search form from shared directory to search directory; the search page requires changes to the search form that are unique to it alone.
Got rid of things (hidden fields, download link) that were added only for the sake of the search page now that it has its own search form.
Fixed bug having to do with coloring of map markers on search page.
Added download button, changed button text for map-clearing button, and added button styles to style element.