Added Requested Feature: Writer Audio lerp toggle (take 3)

[Arylos07]

Description

Added a toggle to Writer Audio so the Writer does not lerp audio while writing. This results in the volume being consistent while writing.

Default and prefab Say Dialogs have this enabled so they will lerp audio by default. The user must change the prefab settings or create a custom Say Dialog to make use of this change.

What is the current behavior?

Issue Number: #929

When using a sound such as typewriters or other effects, the lerping audio can cause the sound to change volume rapidly and not sound consistent. This can be replicated by doing the following:

• Open the WritingSpeedTest scene
• Adjust the writers on the SayDialogs
  • Change beep sounds to contain only the MidVoice sound effect.
• Play the scene.

The sound modulates heavily as it stops and stops. With the other voices, it's not heard, but with one consistent sound effect, the effect is noticeable and causes peaks in the audio levels.

What is the new behavior?

• When Lerp Writer Volume is enabled, the default lerp volume behaviour remains
• When Lerp Writer Volume is disabled, the writer remains at the target volume set by the Writer without lerping.

Important Notes

• My change require modifcations or additions to documentation

  • Possibly, the variable may need to be added as well as a description of what it does. There is a tooltip in the editor that is thorough.

• My change modifies the runtime execution/behaviour of existing Fungus Features. e.g., Say, Menus, Portraits, etc.

Other information

This is a rehash of #934 , but without the stupid mistake that has messed up all of my other PR's. I swear, I know how to use Git.