used .prop() for #grid_snapping_on checkbox state

git-svn-id: http://svg-edit.googlecode.com/svn/trunk@2421 eee81c28-f429-11dd-99c0-75d572ba1ddd
used svgedit.browser checks instead of redefined ones

git-svn-id: http://svg-edit.googlecode.com/svn/trunk@2422 eee81c28-f429-11dd-99c0-75d572ba1ddd
unified overlays styling

git-svn-id: http://svg-edit.googlecode.com/svn/trunk@2423 eee81c28-f429-11dd-99c0-75d572ba1ddd
cleaned indentation in css

git-svn-id: http://svg-edit.googlecode.com/svn/trunk@2424 eee81c28-f429-11dd-99c0-75d572ba1ddd