RichTextLabel's append_bbcode stops animated rich text effects

[lijamez]

Godot version: 3.2.1.stable.official

OS/device including version: Windows 10 version 1909

Issue description:
If a RichTextLabel has BBCode tags that animate the text (such as [tornado] and [shake]) and then append_bbcode function is called, the animations stop.

The documentation for append_bbcode does not suggest this behavior.

Root cause:
set_process_internal(false) is called at the beginning of append_bbcode() and if the bbcode doesn't contain any animated effects, process_internal may not be set to true again.

godot/scene/gui/rich_text_label.cpp

Line 2071 in 5247fdb

set_process_internal(false);

Steps to reproduce:

Create a RichTextLabel, enable BB Code, enter the following as BB Code Text in the inspector:

[color=red]Some red text.[/color] [tornado radius=5 freq=2]Tornado Effect[/tornado] [shake rate=5 level=10]Shake Effect[/shake]

The text will be animated properly.

Then, append any string that does not contain an animated BBCode tag to the label by calling RichTextLabel.append_bbcode("")

Current behavior: Animations are paused.
Expected behavior: Animations continue playing.

Minimal reproduction project:
RTLEffectsDemo.zip

[Eoin-ONeill-Yokai]

I'll get on this --- I wish I could assign myself. :)