allow optionally brace matching with the closing brace to the left of the cursor

this behavior, while slightly less obvious, allows for observing what brace you
just closed. as you write closing braces, the brace you closed gets highlighted

cmd/micro/cellview.go

@@ -73,9 +73,20 @@ func (c *CellView) Draw(buf *Buffer, top, height, left, width int) {
 	// bracePairs is defined in buffer.go
 	if buf.Settings["matchbrace"].(bool) {
 		for _, bp := range bracePairs {
-			r := buf.Cursor.RuneUnder(buf.Cursor.X)
-			if r == bp[0] || r == bp[1] {
+			if buf.Cursor.RuneUnder(buf.Cursor.X) == bp[0] {
 				matchingBrace = buf.FindMatchingBrace(bp, buf.Cursor.Loc)
+				break
+			}
+			left := buf.Cursor.Loc.X
+			if buf.Settings["matchbraceleft"].(bool) {
+				left -= 1
+				if left < 0 {
+					left = 0
+				}
+			}
+			if buf.Cursor.RuneUnder(left) == bp[1] {
+				matchingBrace = buf.FindMatchingBrace(
+					bp, Loc{X: left, Y: buf.Cursor.Loc.Y})
 			}
 		}
 	}

cmd/micro/settings.go

@@ -215,6 +215,7 @@ func DefaultGlobalSettings() map[string]interface{} {
 		"keepautoindent": false,
 		"keymenu":        false,
 		"matchbrace":     false,
+		"matchbraceleft": false,
 		"mouse":          true,
 		"pluginchannels": []string{"https://raw.githubusercontent.com/micro-editor/plugin-channel/master/channel.json"},
 		"pluginrepos":    []string{},
@@ -257,6 +258,7 @@ func DefaultLocalSettings() map[string]interface{} {
 		"indentchar":     " ",
 		"keepautoindent": false,
 		"matchbrace":     false,
+		"matchbraceleft": false,
 		"rmtrailingws":   false,
 		"ruler":          true,
 		"savecursor":     false,