Implement emoji:TextBox

[samhocevar]

emoji:RichTextBox already has a Text property that makes it an acceptable emoji-aware replacement for standard TextBox. However an emoji:TextBox class may make things less confusing for users. Here is a short to-do list:

• inherit from emoji:RichTextBox (I can think of no other way to display images)
• (optionally) inherit from TextBox instead but still use an emoji:RichTextBox internally
• disable style commands (CtrlB etc.)
• disable style and formatting in copy/paste operations
• hide the Document property and related events
• implement and enforce standard TextBox properties: MaxLength, MaxLines etc.

Documentation:

• TextBox
• RichTextBox