Adds matrix sub package & adds polynomial regression series (#36)

* updates

* updates

* tests.

* test coverage

* fixing test

* stride not rows + cols

* lu decomp implementation.

* poly regression!

* poly regression works.

* typo.

matrix/util.go

@@ -0,0 +1,36 @@
+package matrix
+
+import (
+	"math"
+	"strconv"
+)
+
+func minInt(values ...int) int {
+	min := math.MaxInt32
+
+	for x := 0; x < len(values); x++ {
+		if values[x] < min {
+			min = values[x]
+		}
+	}
+	return min
+}
+
+func maxInt(values ...int) int {
+	max := math.MinInt32
+
+	for x := 0; x < len(values); x++ {
+		if values[x] > max {
+			max = values[x]
+		}
+	}
+	return max
+}
+
+func f64s(v float64) string {
+	return strconv.FormatFloat(v, 'f', -1, 64)
+}
+
+func roundToEpsilon(value, epsilon float64) float64 {
+	return math.Nextafter(value, value)
+}