Show more languages?

[bmaupin]

• [x] Add buttons to show more languages
• [x] Properly handle maximum/minimum
• [x] Reset languages when changing chart types?

A few ideas:

• A simple button to toggle between 10 and 15 languages
  • Reduce the width if 15 languages are shown?
• Or a button to show the next 5 languages
  • Remove the previous 5 so only 10 are shown at a time
  • Then we'll probably need an equivalent button to go back (at the top?)

[bmaupin]

Work is being done in show-more-languages branch