Auto pair angle brackets

[An-dz]

This change adds auto-pairing of angle brackets < like it already does with double quotes, parenthesis and square & curly brackets.

The key difference is that it only automatically adds the closing bracket > if you press the opening bracket where it precedes a letter or number. So pressing < after Box will autocomplete to Box<>, but pressing < after a space won't. This way you won't have the closing bracket when trying to write if x < 2.

All other rules of auto-pairing work the same.

I think this is a nice feature when writing generics, traits and pretty much all the stuff we need to put traits or types without messing with the "less than" or "left shift" operands.