Facelift for Proportional Point/Line

A redo of the UI for Proportional Points and Proportional Lines. Main points:

* Ensure sizing consistency and alignment
* Remove all colons
* Fix #474

See #472.

#### Before
![old_point](https://f.cloud.github.com/assets/2470768/798107/ebe459dc-ed59-11e2-8939-41beb1e2acba.png)
![old_line](https://f.cloud.github.com/assets/2470768/798092/743c1140-ed59-11e2-82c7-72f7dc9bf468.png)

#### After
![new_point](https://f.cloud.github.com/assets/2470768/798108/f08d2b76-ed59-11e2-906e-d550f192358f.png)
![new_line](https://f.cloud.github.com/assets/2470768/798093/79ec5960-ed59-11e2-9bcd-d5059292401d.png)