DEV-1313: Add additional map types (#76)

* add helper to draw a ring of hazards

* refactor tests to not be internal tests

* add "hz_inner_wall" map

* add "hz_rings" map

* fix map registry

* fix: edge case bugs in drawRing

* remove println

* add "hz_columns"

* add "hz_rivers_bridges" map

* WIP: implementing spiral hazards map

* finish basic testing of 'hz_spiral'

* include first turn

* add "hz_hazards" map

* remove incorrect author

* add "hz_grow_box" map

* add "hz_expand_box" map

* add "hz_expand_scatter" map

* remove debug

* document the new "Range" method

* - use rules.RulesetError instead of generic error
- use a rules.Point for map rivers and bridgets map key

* use rules.RulesetError instead of errors.New

* provide more detail about boundar conditions

* fix documentation (max can be == min)

* add unit tests

rand.go

@@ -4,6 +4,10 @@ import "math/rand"
 
 type Rand interface {
 	Intn(n int) int
+	// Range produces a random integer in the range of [min,max] (inclusive)
+	// For example, Range(1,3) could produce the values 1, 2 or 3.
+	// Panics if max < min (like how Intn(n) panics for n <=0)
+	Range(min, max int) int
 	Shuffle(n int, swap func(i, j int))
 }
 
@@ -12,6 +16,10 @@ var GlobalRand globalRand
 
 type globalRand struct{}
 
+func (globalRand) Range(min, max int) int {
+	return rand.Intn(max-min+1) + min
+}
+
 func (globalRand) Intn(n int) int {
 	return rand.Intn(n)
 }
@@ -36,6 +44,10 @@ func (s seedRand) Intn(n int) int {
 	return s.rand.Intn(n)
 }
 
+func (s seedRand) Range(min, max int) int {
+	return s.rand.Intn(max-min+1) + min
+}
+
 func (s seedRand) Shuffle(n int, swap func(i, j int)) {
 	s.rand.Shuffle(n, swap)
 }
@@ -51,6 +63,10 @@ func (minRand) Intn(n int) int {
 	return 0
 }
 
+func (minRand) Range(min, max int) int {
+	return min
+}
+
 func (minRand) Shuffle(n int, swap func(i, j int)) {
 	// no shuffling
 }
@@ -64,6 +80,10 @@ func (maxRand) Intn(n int) int {
 	return n - 1
 }
 
+func (maxRand) Range(min, max int) int {
+	return max
+}
+
 func (maxRand) Shuffle(n int, swap func(i, j int)) {
 	// rotate by one element so every element is moved
 	if n < 2 {