Enabled other month cell text and attributes to be changed with block parameter.

[lkol]

Modified the helper to allow setting the cell text or the attributes for the previous or next month with a block.

The code below used to only affect the current month, not the other months' cells (with a class "otherMonth" be default):

calendar(:year => 2005, :month => 5) do |d|
    [d.mday, {:class => "myCustomClass"}]
end

After this change, also other months' cells can be customized with the block.

[sgreenfield]

+1 This should be merged.

[sidereel-dev]

Thank you for this, saved a bunch of time

[lkol]

My pleasure!