Facelift for certain symbolizer interfaces

This facelift applies in particular to "Point symbolizer" and "Unique symbolizer - point".

* Rearrange panels into a 2x2 grid rather than all vertical
* Remove all colons
* Rename configuration --> settings
* Center text in drop-down menus
* Replace JNumericSpinner (OrbisGIS SIF) --> JSpinner (pure Java)
* Resize Simple Style Editor
* Right-align text fields and labels
* Replace JTextField --> JFormattedTextField (with NumberFormat model)
  to verify input
* Remove unnecessary JPanels
* Put preview in its own (titled) panel and make background transparent
* Resize color previews
* Put checkbox next to its text; put color preview and checkbox on the
  same line
* Remove unnecessary qualifiers (e.g., Line width --> Width)
* Ensure component size consistency

#### Before
![old](https://f.cloud.github.com/assets/2470768/715062/21d50a30-df10-11e2-8566-550fed9734ca.png)

#### After
![new](https://f.cloud.github.com/assets/2470768/715063/2542100a-df10-11e2-8035-36698b06cb2a.png)