Add --cursor-line to highlight the whole current line

Similar to 'set cursorline' of Vim.

man/man1/fzf.1

@@ -534,6 +534,9 @@ color mappings.
          --color='pointer:#E12672,marker:#E17899,prompt:#98BEDE,hl+:#98BC99'\fR
 .RE
 .TP
+.B "--cursor-line"
+Highlight the whole current line
+.TP
 .B "--no-bold"
 Do not use bold text
 .TP

src/options.go

@@ -92,6 +92,7 @@ const Usage = `usage: fzf [options]
     --ansi                 Enable processing of ANSI color codes
     --tabstop=SPACES       Number of spaces for a tab character (default: 8)
     --color=COLSPEC        Base scheme (dark|light|16|bw) and/or custom colors
+    --cursor-line          Highlight the whole current line
     --no-bold              Do not use bold text
 
   History
@@ -322,6 +323,7 @@ type Options struct {
 	MinHeight    int
 	Layout       layoutType
 	Cycle        bool
+	CursorLine   bool
 	KeepRight    bool
 	Hscroll      bool
 	HscrollOff   int
@@ -1948,6 +1950,10 @@ func parseOptions(opts *Options, allArgs []string) error {
 			opts.Layout = layoutDefault
 		case "--cycle":
 			opts.Cycle = true
+		case "--cursor-line":
+			opts.CursorLine = true
+		case "--no-cursor-line":
+			opts.CursorLine = false
 		case "--no-cycle":
 			opts.Cycle = false
 		case "--keep-right":

src/terminal.go

@@ -229,6 +229,7 @@ type Terminal struct {
 	printQuery         bool
 	history            *History
 	cycle              bool
+	cursorLine         bool
 	headerVisible      bool
 	headerFirst        bool
 	headerLines        int
@@ -754,6 +755,7 @@ func NewTerminal(opts *Options, eventBox *util.EventBox, executor *util.Executor
 		executor:           executor,
 		paused:             opts.Phony,
 		cycle:              opts.Cycle,
+		cursorLine:         opts.CursorLine,
 		headerVisible:      true,
 		headerFirst:        opts.HeaderFirst,
 		headerLines:        opts.HeaderLines,
@@ -1912,10 +1914,19 @@ func (t *Terminal) printItem(result Result, line int, i int, current bool, bar b
 		}
 		newLine.width = t.printHighlighted(result, tui.ColNormal, tui.ColMatch, false, true)
 	}
+	if current && t.cursorLine {
+		maxWidth := t.window.Width() - (t.pointerLen + t.markerLen + 1)
+		fillSpaces := maxWidth - newLine.width
+		newLine.width = maxWidth
+		if fillSpaces > 0 {
+			t.window.CPrint(tui.ColCurrent, strings.Repeat(" ", fillSpaces))
+		}
+	} else {
 		fillSpaces := prevLine.width - newLine.width
 		if fillSpaces > 0 {
 			t.window.Print(strings.Repeat(" ", fillSpaces))
 		}
+	}
 	printBar()
 	t.prevLines[i] = newLine
 }