Add brace highlighting

Use the 'matchbrace' option which is off by default.

Ref #853

cmd/micro/settings.go

@@ -214,6 +214,7 @@ func DefaultGlobalSettings() map[string]interface{} {
 		"infobar":        true,
 		"keepautoindent": false,
 		"keymenu":        false,
+		"matchbrace":     false,
 		"mouse":          true,
 		"pluginchannels": []string{"https://raw.githubusercontent.com/micro-editor/plugin-channel/master/channel.json"},
 		"pluginrepos":    []string{},
@@ -255,6 +256,7 @@ func DefaultLocalSettings() map[string]interface{} {
 		"ignorecase":     false,
 		"indentchar":     " ",
 		"keepautoindent": false,
+		"matchbrace":     false,
 		"rmtrailingws":   false,
 		"ruler":          true,
 		"savecursor":     false,