Additions to config list

I got a list of the config strings from https://github.com/jigish/slate/wiki/Global-Configs and tested that list against the configs listed in `Slate.tmLanguage` and `Slate.JSON-tmLanguage`.

The changes:
* `switchSelectedBackgroundC` changed to `switchSelectedBackgroundColor`
* `windowHintsIgnoreHiddenW` changed to `windowHintsIgnoreHiddenWindows`
* Add `windowHintsRoundedCornerSize` 
* `windowHintsSpreadSearchHe` changed to `windowHintsSpreadSearchHeight`
* Add `windowHintsSpreadSearchWidth`