Enable script calls from texboxes

[audinowho]

This issue is made to encapsulate the proposed feature of allowing textboxes to call script functions. This way, cutscene events can happen in the middle of a textbox. It is planned to work like such:

The developer will call a TextDialogue function from script, this time with a table of Lua function pointers in addition to the Text parameter. The dialogue text will contain [script=<script number>] tags to denote at which point in the text the script should fire. Example:

local callbacks = { foxFunction, jumpFunction, lazyFunction }
TextDialogue("The quick brown fox [script=0] jumped [script=1] over the lazy [script=2] dog.", callbacks, waitTime)

Current work has already added support for the [script] tag (found in Text.cs) and stubbed out a function in ScriptUI.cs.
Additionally, the script tags in DialogueBox.cs are properly read and stored.

Remaining work to be done/figured out:

• The table of lua function calls must be passed into the dialoguebox and stored there.
• When the script tag is hit, must call the lua function as a coroutine and WAIT for it to complete. This can be done by setting MenuManager.Instance.NextAction.

The TODOs on ScriptUI.cs and DialogueBox.cs denote the places where this is expected to be added.