Experimental implementation of "reload" action

# Reload input list with different sources
  seq 10 | fzf --bind 'ctrl-a:reload(seq 100),ctrl-b:reload(seq 1000)'

  # Reload as you type
  seq 10 | fzf --bind 'change:reload:seq {q}' --phony

  # Integration with ripgrep
  RG_PREFIX="rg --column --line-number --no-heading --color=always --smart-case "
  INITIAL_QUERY=""
  FZF_DEFAULT_COMMAND="$RG_PREFIX '$INITIAL_QUERY'" \
    fzf --bind "change:reload:$RG_PREFIX {q} || true" \
        --ansi --phony --query "$INITIAL_QUERY"

Close #751
Close #965
Close #974
Close #1736
Related #1723

src/matcher.go

@@ -12,10 +12,11 @@ import (
 
 // MatchRequest represents a search request
 type MatchRequest struct {
-	chunks  []*Chunk
-	pattern *Pattern
-	final   bool
-	sort    bool
+	chunks     []*Chunk
+	pattern    *Pattern
+	final      bool
+	sort       bool
+	clearCache bool
 }
 
 // Matcher is responsible for performing search
@@ -69,7 +70,7 @@ func (m *Matcher) Loop() {
 			events.Clear()
 		})
 
-		if request.sort != m.sort {
+		if request.sort != m.sort || request.clearCache {
 			m.sort = request.sort
 			m.mergerCache = make(map[string]*Merger)
 			clearChunkCache()
@@ -221,7 +222,7 @@ func (m *Matcher) scan(request MatchRequest) (*Merger, bool) {
 }
 
 // Reset is called to interrupt/signal the ongoing search
-func (m *Matcher) Reset(chunks []*Chunk, patternRunes []rune, cancel bool, final bool, sort bool) {
+func (m *Matcher) Reset(chunks []*Chunk, patternRunes []rune, cancel bool, final bool, sort bool, clearCache bool) {
 	pattern := m.patternBuilder(patternRunes)
 
 	var event util.EventType
@@ -230,5 +231,5 @@ func (m *Matcher) Reset(chunks []*Chunk, patternRunes []rune, cancel bool, final
 	} else {
 		event = reqRetry
 	}
-	m.reqBox.Set(event, MatchRequest{chunks, pattern, final, sort && pattern.sortable})
+	m.reqBox.Set(event, MatchRequest{chunks, pattern, final, sort && pattern.sortable, clearCache})
 }