admin css tweaks

[Denis-de-Bernardy]

the ".inside li" makes the category picker look a bit bad, so needs to be fixed, but the idea in the first is to allow lists to be inserted in editor meta boxes, and help items, added by plugins.

the other one is to make the postname field occupy the full width.

#contextual-help-wrap li,
.inside li {
	margin-left: 1.8em;
	list-style: square;
}

input#post_name {
	width: 99%;
}

Lists are typically used for containers so changing this could affect many plugins. There are global list styles defined in global.css: ul-disc, ul-square and ol-decimal that can be used when needed.

Attached patch isn't working, but I'll get one that does when I look into adding my plugin's help items. The need to add classes all over the place removes the possibility to use markdown to quick format help screens.