getDisplayIndentGuides() call fails since v1.17.0

[exsilium]

Describe the bug

With the es6 class refactoring it seems that getDisplayIndentGuides fails as the renderer function cannot be found: this.renderer.getDisplayIndentGuides is not a function

Virtual renderer function name is in singular form and missing an s: https://github.com/ajaxorg/ace/blame/bc93f987f929453c4f99b7070ad4cdc394578afb/src/virtual_renderer.js#L465

Expected Behavior

getDisplayIndentGuides should return the option value (boolean)

Current Behavior

getDisplayIndentGuides is not working as the renderer function is not found.

Reproduction Steps

Use the VirtualRenderer API call as described in: https://ace.c9.io/api/classes/Ace.VirtualRenderer.html#getDisplayIndentGuides

Possible Solution

Fix the virtual renderer function name to be in plural form.

Additional Information/Context

No response

Ace Version / Browser / OS / Keyboard layout

v1.17.0 / Chrome, Safari / MacOS / Nordic

[whazor]

Merged, will be released in next version.