PHP Geocode Address Formatter: Parse a location string and returns its details

Class Geocode

This is a lightweight class that normalizes geocodes (Lat,Lng pairs).  It has a single
method, the constructor, which receives a geocode string in any of several common and 
very relaxed formats.  See the "demo" file for examples.

The constructor attempts to interpret the input string.  It returns an instance of the
Geocode object with public properties as shown below.  If it's impossible to make sense
of the input, the "error" property will have some explanation of what went wrong.  If
"error" is not empty, you should not rely on the other values in the object.

This shows the Geocode object for the Post Office at ZIP code 15213 in Pittsburgh:

Geocode Object
(
    [name] => Post Office 15213 in Pittsburgh
    [lat] => 40.4401766
    [lng] => -79.9526167
    [geo] => 40.4401766,-79.9526167
    [lat_dms] => 40°26'24.636"N
    [lng_dms] => 79°57'9.42"W
    [geo_dms] => 40°26'24.636"N,79°57'9.42"W
    [lat_dmd] => 40°26.4106'N
    [lng_dmd] => 79°57.157'W
    [geo_dmd] => 40°26.4106'N,79°57.157'W
    [lat_dd] => 40.4401766°N
    [lng_dd] => 79.9526167°W
    [geo_dd] => 40.4401766°N,79.9526167°W
    [olc] => 87G2C2RW+3X
    [input] => 40.4401766,-79.9526167
    [error] => 
)

You must provide a geocode string or an open location code string to use the object.  
You may provide an optional name that can identify the place the geocode points to.

To get this object, create an instance of Geocode like these:

    require_once('class_Geocode.php'); 
    $geo = new Geocode('40.4401766,-79.9526167', 'Post Office 15213 in Pittsburgh');

To use this object, first check $geo->error for empty() status, then you can get any
of the properties that make sense for your application, eg:

    echo $geo->geo_dms; // prints 40°26'24.636"N,79°57'9.42"W 
    echo $geo->olc;     // prints 87G2C2RW+3X 

Reconstruction of Lat,Lng pairs is accurate when using explicit geocodes because the
geocode points to a place on earth.  Accuracy is a bit less when using an open location 
code.  A 10-digit plus code has only about "rooftop" accuracy; the generated geocode 
will point to the southwest corner of the area defined by the OLC.

References:
    https://journeynorth.org/tm/LongitudeIntro.html
    https://en.wikipedia.org/wiki/Horizontal_position_representation
    https://en.wikipedia.org/wiki/Geographic_coordinate_system
    https://en.wikipedia.org/wiki/Decimal_degrees
    https://en.wikipedia.org/wiki/Open_Location_Code