Remove class fc-weeknr-daycell

As suggested by arshaw, a separate class `fc-weeknr-daycell` was not
necessary. To target a week number:
- in a day cell, use `.fc-day-top .fc-week-number`
- in a column, use `td.fc-week-number`

src/basic/basic.css

@@ -40,18 +40,18 @@
 	padding-bottom: 2px;
 }
 
-.fc-basic-view td.fc-day-top span.fc-weeknr-daycell {
+.fc-basic-view td.fc-day-top span.fc-week-number {
 	width: 1.5em;
 	text-align: center;
 	background-color: #f2f2f2;
 	color: #808080;
 }
 
-.fc-ltr .fc-basic-view td.fc-day-top span.fc-weeknr-daycell {
+.fc-ltr .fc-basic-view td.fc-day-top span.fc-week-number {
 	border-radius: 0 0 3px 0;
 }
 
-.fc-rtl .fc-basic-view td.fc-day-top span.fc-weeknr-daycell {
+.fc-rtl .fc-basic-view td.fc-day-top span.fc-week-number {
 	border-radius: 0 0 0 3px;
 }
 

src/common/DayGrid.js

@@ -159,7 +159,7 @@ var DayGrid = FC.DayGrid = Grid.extend(DayTableMixin, {
 		return '' +
 			'<td class="' + classes.join(' ') + '" data-date="' + date.format() + '">' +
 				((this.view.cellWeekNumbersVisible && (date.day() === weekCalcFirstDoW)) ?
-					'<span class="fc-week-number fc-weeknr-daycell">' +
+					'<span class="fc-week-number">' +
 						date.format('w') +
 					'</span>' :
 					''