Two features: page menu and custom filters

Add all reports dynamically into the page menu. The layout xml will unset the original page menu block and adds the clean page menu block. If you find any other possibility for injecting dynamic menu items let me know asap :-) You have to clear the cache if you change the title or add/remove a new report.

Second feature adds the possibility for custom filters for columns in the Report/View/Grid.php file.

Auto reformatting also removed some superfluous whitespaces / tabs ;-)
I've added the feature so you can also specify the filter to use as well, and the function is backwards compatible with the old method as well.

Here are JSON examples using the new and old method. This could also be extended for us to just specify a simpler name for the type, like "text" and "date" and map that to the full type name:

JSON including type:
{
  "filterable": {
    "customer_id" : "adminhtml/widget_grid_column_filter_select",
    "count" : "adminhtml/widget_grid_column_filter_text",
    "created_at" : "adminhtml/widget_grid_column_filter_date"
  }
}

Old JSON which still works:
{
  "filterable": [
	"created_at"
  ]
}

Some types, such as "select" won't work though straight off, we'd need to add functions to such where the user would also specify the options for the select.