themes lib MDL-24895 Multiple fixes to better handle overflow.

Major tasks undertaken in this patch:
* New format_text argument, overflowdiv.
* New page layout Report.
* Review of all format_text calls.
* Added support for the report layout to all themes.
* Changed forum post display from tables to divs.

mod/assignment/styles.css

@@ -10,8 +10,6 @@
 .path-mod-assignment .feedback .from {float: left;}
 .path-mod-assignment .files img {margin-right: 4px;}
 .path-mod-assignment .files a {white-space:nowrap;}
-.path-mod-assignment .flexible-wrap {width:100%;overflow:auto;}
-.path-mod-assignment .flexible-wrap > .flexible {margin:0;}
 .path-mod-assignment .late {color: red;}
 
 /** Styles for submissions.php **/