Tips: use as more general percentage calculator.

The guts were already here, just made them all work properly.

- Greatly expand triggering and allow guard to kick back false
  positives
- Use NumberStyler to handle and "make pretty" a variety of number
  formats
- Use named captures to make things easier to follow.

Fixes #690.
Merge pull request #691 from mwmiller/tipsy

Tips: use as more general percentage calculator.
Conversions: Upgrading to 0.24 to support areas and volumes; adding tests to prove new units
Merge pull request #694 from duckduckgo/mintsoft/conversions_squared_cubed

Conversions: Upgrading to 0.24 to support areas and volumes
DuckDuckGo: add t-shirt options.

As many reasonable aliases of which I could think.

Fixes #676.
Merge pull request #695 from mwmiller/shirts

DuckDuckGo: add t-shirt options.
add hex/base64 formatting option to md5 goodie
minor code style tweaks to MD5 goodie
Merge pull request #696 from jarmokivekas/unify-md5-sha-hash

Add hex/base64 formatting option to md5 goodie