Specify south west corner is included, add test cases

Documentation/Plus Codes Specification.md

@@ -17,10 +17,10 @@ All substantial changes changes to this document are listed here.
 A **Plus Code** represents a locus of coordinates ("**area**") with **bounds** on northern & southern parallels and western & eastern meridians. This area includes exactly the coordinates:
 
 1. Inside (excluding) the bounds;
-2. On the eastern bound between (excluding) the northern and southern bounds;
+2. On the western bound between (excluding) the northern and southern bounds;
 3. (If the northern bound is 90° N and the western bound is 180° W) the North Pole (i.e. the point at 90° N);
 4. (If the southern bound is 90° S and the western bound is 180° W) the South Pole (i.e. the point at 90° S); and
-5. (If the southern bound is not 90° S) on the southern bound from (excluding) the western bound to (including) the eastern bound.
+5. (If the southern bound is not 90° S) on the southern bound from (including) the western bound to (excluding) the eastern bound.
 
 This specification references latitudes and longitudes on Earth under [WGS 84](https://earth-info.nga.mil), which is the standard used by the Global Positioning System. If another geodetic is used, that context MUST be agreed between the producer and consumer of a Plus Code.
 

test_data/encoding.csv

@@ -17,6 +17,17 @@
 0.5,179.5,4,6VGX0000+
 1,1,11,6FH32222+222
 ################################################################################
+# Corners and edges of bounds
+# Plus Codes Specification:
+# > This area includes exactly the coordinates:...
+# > 1. Inside (excluding) the bounds;
+0,0.1,2,6F000000+
+# > 2. On the western bound between (excluding) the northern and southern bounds;
+0,0,2,6F000000+
+# > 5. (If the southern bound is not 90° S) on the southern bound from (excluding) the western bound to (including) the eastern bound.
+-10,0,2,6F000000+
+-10,0.1,2,6F000000+
+################################################################################
 # North Pole and latitudes > 90N
 # Plus Codes Specification:
 # > This area includes exactly the coordinates:...