Add new features

[kylebmeredith]

• add an "init" button to the tox table that will load the tox from disk
• add a filter button to control whether only dirty toxes are shown (or all external toxes)
• sort the tox table by op name
• allow customization of default externalization parameters
• add a toggle to control whether to create a subfolder for the tox
• check to see if the tox is being saved in the palette folder. If it is, use an expression (this copies the behavior when the path is set through the Touch UI)
• make the popup window a bit wider
• change the header to say "External Tox Components", since now it doesn't only show dirty ones

[raganmd]

Hey @kylebmeredith - this PR isn't forgotten, I've just been waiting on changes coming to external file handling. I have a big chunk of new features that are going to get added, and I'll do my best to include what you have here though there may be some breaking changes in the next version. :/