Default 2nd argument for setFilter and setWrap

Issue #501 resolved
hahawoo
created an issue

I'd assume that more often than not, lovers would want to set the same value for both arguments of Image/Canvas:setFilter/setWrap and love.graphics.setDefaultImageFilter.

Perhaps these functions could set both values when called with one argument. For example, Image:setFilter('nearest') becomes equivalent to Image:setFilter('nearest', 'nearest').