Make CoreText manage the tabs

Rather than putting tabs in their own node, leave them in the text nodes and allow core text to handle the size. This fixes the issue with using tabs in right-to-left text.
Add space invisible

The implements the space invisible using the new method of drawing the invisibles so it does not affect right-to-left text.
Do not create tab stop at location zero

I do not understand what the point of this tab stop is.
Do not create temporary CTLineRef for lines without tabs

This also avoids creating the paragraph style object for these lines.
Check for failure when creating CTLineRef related objects
Use ruby18 shebang in bundle command template
Use our “standard” idiom for setting menu item keys to ⌘1-n
Extend bundle item chooser’s search capabilities