Tidying Admin CSS, bringing it up to CSS Code Standards (work in progress)

[georgestephanis]

as per ​http://codex.wordpress.org/CSS_Coding_Standards, this is an attempt to bring the internal admin stylesheets up to CSS Coding Standards

Some of the changes being made are ...

Properly intenting top: left: right: bottom: attributes two tabs when following a position:absolute position:fixed or position:relative declaration
Alphabetizing css properties
Removing unnecessary browser prefixes
Placing browser prefixed css properties before the non-browser prefixed versions
Removing extraneous spaces
Applying a consistent ordering of browser-prefixed properties (based on length of prefix to get an aesthetically pleasing diagonal line, rather than jagged, inconsistent line endings -- yes, I know it's silly, but it's better than randomness, and alphabetical isn't as useful)
Applying a uniform method to attribute selectors and url references by wrapping double-quotes around the values (there was no prior standard and a motley assortment of usages)
Changing colors to 3-character shorthand ( 888888 becomes 888 )
Changing colors to lower case ( EEE becomes eee )

and probably a couple others that aren't coming to mind right now.

First draft -- more revisions pending