More iterative algorithms

- Add RunIterator and decoder from RLE
 - Add BitIterator and BitsFromRuns
 - Add BitsFromSlice
 - Add RunsFromBits

License: MIT
Signed-off-by: Jakub Sztandera <kubuxu@protonmail.ch>

lib/rlepluslazy/interface.go

@@ -0,0 +1,24 @@
+package rlepluslazy
+
+type Run struct {
+	Val bool
+	Len uint64
+}
+
+func (r Run) Valid() bool {
+	return r.Len != 0
+}
+
+type RunIterator interface {
+	NextRun() (Run, error)
+	HasNext() bool
+}
+
+type RunIterable interface {
+	RunIterator() (RunIterator, error)
+}
+
+type BitIterator interface {
+	Next() (uint64, error)
+	HasNext() bool
+}